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SUMMARY TECHNICAL REPORT 
OF THE 

NATIONAL DEFENSE RESEARCH COMMITTEE 


Manuscript and illustrations for this volume were prepared for 
publication by the Summary Reports Group of the Columbia 
University Division of War Research under contract OEMsr-1131 
with the Office of Scientific Research Development. This vol¬ 
ume was printed and bound by the Columbia University Press. 

Distribution of the Summary Technical Report of NDRC has 
been made by the War and Navy Departments. Inquires concern¬ 
ing the availability and distribution of the Summary Technical 
Report volumes and microfilmed and other reference material 
should he addressed to the War Department Library, Room 
1A-522, The Pentagon, Washington 25, D.C., or to the Office of 
Naval Research, Navy Department, Attention: Reports and Docu¬ 
ments Section, Washington 25, D.C. 

Copy No. 

6 


This volume, like the seventy others of the Summary Technical 
Report of NDRC, has been written, edited, and printed under 
great pressure. Inevitably there are errors which have slipped past 
Division readers and proofreaders. There may he errors of fact not 
known at time of printing. The author has not been able to follow 
through his writing to the final page proof. 

Please report errors to : 

JOINT RESEARCH AND DEVELOPMENT BOARD 
PROGRAMS DIVISION (STR ERRATA) 

WASHINGTON 25, D.C. 

A master errata sheet will he compiled from these reports and sent 
to recipients of the volume. Your help will make this book more 
useful to other readers and will be of great value in preparing any 
revisions. 


SUMMARY TECHNICAL REPORT OF DIVISION 11, NDRC 


VOLUME 1 


IMPROVED EQUIPMENT FOR 


OXYGEN PRODUCTION 


OFFICE OF SCIENTIFIC RESEARCH AND DEVELOPMENT 
VANNEVAR BUSH, DIRECTOR 

NATIONAL DEFENSE RESEARCH COMMITTEE 
JAMES B. CONANT, CHAIRMAN 

DIVISION 11 
H. M. CHADWELL, CHIEF 


WASHINGTON, D.C., 1946 




NATIONAL DEFENSE RESEARCH COMMITTEE 


James B. Conant, Chairman 
Richard C. Tolman, Vice Chairman 
Roger Adams Army Representative 1 

Frank B. Jewett Navy Representative 2 

Karl T. Compton Commissioner of Patents 2 

Irvin Stewart, Executive Secretary 


1 Army Representatives in order of sendee: 

Maj. Gen. G. V. Strong Col. L. A. Denson 

Maj. Gen. R. C. Moore Col. P. R. Faymonville 

Maj. Gen. C. C. Williams Brig. Gen. E. A. Regnier 

Brig. Gen. W. A. Wood, Jr. Col. M. M. Irvine 

Col. E. A. Routheau 


- Nai’y Representatives in order of service: 

Rear Adm. H. G. Bowen Rear Adm. J. A. Furer 

Capt. Lybrand P. Smith Rear Adm. A. H. Van Keuren 

Commodore H. A. Schade 

Commissioners of Patents in order of sendee: 
Conway P. Coe Casper W. Ooms 


NOTES ON THE ORGANIZATION OF NDRC 


The duties of the National Defense Research Committee 
were (1) to recommend to the Director of OSRD suitable 
projects and research programs on the instrumentalities of 
warfare, together with contract facilities for carrying out 
these projects and programs, and (2) to administer the tech¬ 
nical and scientific work of the contracts. More specifically, 
NDRC functioned by initiating research projects on requests 
from the Army or the Navy, or on requests from an allied 
government transmitted through the Liaison Office of OSRD, 
or on its own considered initiative as a result of the experi¬ 
ence of its members. Proposals prepared by the Division, 
Panel, or Committee for research contracts for performance 
of the work involved in such projects were first reviewed by 
NDRC, and if approved, recommended to the Director of 
OSRD. Upon approval of a proposal by the Director, a con¬ 
tract permitting maximum flexibility of scientific effort was 
arranged. The business aspects of the contract, including 
such matters as materials, clearances, vouchers, patents, 
priorities, legal matters, and administration of patent matters 
were handled by the Executive Secretary of OSRD. 

Originally NDRC administered its work through five 
divisions, each headed by one of the NDRC members. 
These were: 

Division A—Armor and Ordnance 

Division B—Bombs, Fuels, Gases, & Chemical Problems 
Division C—Communication and Transportation 
Division D—Detection, Controls, and Instruments 
Division E—Patents and Inventions 


In a reorganization in the fall of 1942, twenty-three ad¬ 
ministrative divisions, panels, or committees were created, 
each with a chief selected on the basis of his outstanding 
work in the particular field. The NDRC members then be¬ 
came a reviewing and advisory group to the Director of 
OSRD. The final organization was as follows : 


Division 1—Ballistic Research 

Division 2—Effects of Impact and Explosion 

Division 3—Rocket Ordnance 

Division 4—Ordnance Accessories 

Division 5—New Missiles 

Division 6—Sub-Surface Warfare 

Division 7—Fire Control 

Division 8—Explosives 

Division 9—Chemistry 

Division 10—Absorbents and Aerosols 

Division 11—Chemical Engineering 

Division 12—Transportation 

Division 13—Electrical Communication 

Division 14—Radar 

Division 15—Radio Coordination 

Division 16—Optics and Camouflage 

Division 17—Physics 

Division 18—War Metallurgy- 

Division 19—Miscellaneous 

Applied Mathematics Panel 

Applied Psychology Panel 

Committee on Propagation 

Tropical Deterioration Administrative Committee 



NDRC FOREWORD 


As events of the years preceding 1940 revealed 
x\.niore and more clearly the seriousness of the 
world situation, many scientists in this country came 
to realize the need of organizing scientific research 
for service in a national emergency. Recommenda¬ 
tions which they made to the White House were 
given careful and sympathetic attention, and as a 
result the National Defense Research Committee 
[NDRC] was formed hy Executive Order of the 
President in the summer of 1940. The members of 
NDRC, appointed by the President, were instructed 
to supplement the work of the Army and the Navy 
in the development of the instrumentalities of war. 
A year later, upon the establishment of the Office 
of Scientific Research and Development [OSRDJ, 
NDRC became one of its units. 

The Summary Technical Report of NDRC is a 
conscientious effort on the part of NDRC to sum¬ 
marize and evaluate its work and to present it in a 
useful and permanent form. It comprises some 
seventy volumes broken into groups corresponding 
to the NDRC Divisions, Panels, and Committees. 

The Summary Technical Report of each Division, 
Panel, or Committee is an integral survey of the work 
of that group. The first volume of each group’s report 
contains a summary of the report, stating the prob¬ 
lems presented and the philosophy of attacking them, 
and summarizing the results of the research, develop¬ 
ment, and training activities undertaken. Some vol¬ 
umes may he "state of the art" treatises covering 
subjects to which various research groups have con¬ 
tributed information. Others may contain descrip¬ 
tions of devices developed in the laboratories. A 
master index of all these divisional, panel, and com¬ 
mittee reports which together constitute the Sum¬ 
mary Technical Report of NDRC is contained in 
a separate volume, which also includes the index of 
a microfilm record of pertinent technical laboratory 
reports and reference material. 

Some of the NDRC-sponsored researches which 
had been declassified by the end of 1945 were of 
sufficient popular interest that it was found desirable 
to report them in the form of monographs, such as 
the series on radar by Division 14 and the mono¬ 
graph on sampling inspection by the Applied Mathe¬ 
matics Panel. Since the material treated in them 
is not duplicated in the Summary Technical Report 
of NDRC, the monographs are an important part of 
the story of these aspects of NDRC research. 


In contrast to the information on radar, which is 
of widespread interest and much of which is released 
to the public, the research on subsurface warfare is 
largely classified and is of general interest to a more 
restricted group. As a consequence, the report of 
Division 6 is found almost entirely in its Summary 
Technical Report, which runs to 23 volumes. The 
extent of the work of a division cannot therefore be 
judged solely by the number of volumes devoted to 
it in the Summary Technical Report of NDRC: 
account must be taken of the monographs and avail¬ 
able reports published elsewhere. 

One can claim on behalf of Division 11 that the 
results of its work contributed directly and dramati¬ 
cally to the successful prosecution and triumphant 
termination of World War II. It was Division 11, 
under the leadership first of R. P. Russell, then 
E. P. Stevenson, and later H. M. Chadwell, which 
developed the incendiary bombs with which Japan’s 
industrial plants were reduced to ashes. Filled with 
jellied gasoline, the AN-M69 incendiary was credited 
with the highest efficiency of any bomb against Japa¬ 
nese factories and dwellings. More than 40,000 tons 
of AN-M69 bombs were dropped on Japanese cities. 

Division 11 likewise applied the use of thickened 
fuels to portable and mechanized flame throwers, 
which were emploved with great success against the 
enemy in the Pacific. Other sections of the Division 
did important work in developing improved tech¬ 
niques for the production of oxygen for military uses, 
and in solving numerous other problems in the field 
of chemical engineering, one of the most valuable 
contributions being the development of new hydraulic 
fluids. 

This Summary Technical Report of Division 11. 
prepared under the direction of the Division Chief 
and authorized hy him for publication, describes the 
activities of the Division and its contractors. It stands 
as a testimonial to the imagination and resourceful¬ 
ness of American scientists and industrial engineers 
and as a record of wartime accomplishment worthy 
of grateful recognition. 

Vannevar Bush, Director 
Office of Scientific Research and Development 

J. B. Conant, Chairman 
National Defense Research Committee 





FOREWORD 


F or administrative purposes and because of the 
diverse nature of the problems studied by Divi¬ 
sion 11 (Chemical Engineering) of NDRC, three 
independent sections were created: Section 11.1 
(Oxygen Problems); Section 11.2 (Miscellaneous 
Chemical Engineering Problems), and Section 11.3 
(Fire Warfare). The work of each of the three sec¬ 
tions is presented in an individual volume of the 
Summary Technical Report. 

The work of Section 11.1 had to do primarily with 
the production and use of oxygen. The oxygen pro¬ 
gram was extensive and covered the interests of the 
three Services—Navy, Army, and Air Forces. This 
work was carried out under the direction of R. P. 
Russell (January and February 1943), E. P. Steven¬ 
son (March 1943 to February 1945), and Dr. H. M. 
Chad well (March 1945 to termination) as Chiefs of 
Division 11 for the periods indicated, and of E. P. 
Stevenson (October 1940 to March 1943) and Dr. 
J. H. Rushton (June 1943 to termination) as Chiefs 
of Section 11.1. Assisting them were Dr. C. C. 
Furnas as Chief Technical Aide, and Dr. S. S. Pren¬ 
tiss and D. Churchill, Jr., as Technical Aides of 
Section 11.1. 

In the fall of 1940 a long-range project was initi¬ 
ated which required the use of large quantities of 
liquid oxygen as a secondary fuel for underwater 
propulsion of submarines. The project called for a 
means to generate oxygen at sea when the submarine 
was surfaced, and this posed an extreme problem in 
design of liquid-oxygen producing equipment. 

Soon after work was started on oxygen for sub¬ 
marine propulsion, an interservice committee was set 
up to coordinate the oxygen needs of all Services. 
The Army Corps of Engineers had a need for light¬ 
weight field generating units to supply medical and 
repair facilities. The Army Air Forces projected 
large requirements for field generation of high-purity 
oxygen for aviation breathing purposes. Such field 
units were to he airborne, truck, or skid mounted, 
and were to he used in flight and at advanced bases. 
The Navy Bureau of Aeronautics had similar re¬ 
quirements, and the Navy Bureau of Ships needed 
plants for production of oxygen for repair purposes 
on shipboard. 


Problems closely associated with the use of oxygen, 
such as removal of carbon dioxide from a submarine 
atmosphere, and the disposal of the exhaust gases 
from oil-oxygen fired Diesel or gas turbines in sub¬ 
marines, were also handled and working models were 
built. 

The oxygen program not only involved the design 
of complete generating plants, hut also the develop¬ 
ment of vaporizers whereby liquid oxygen could be 
converted to gaseous oxygen for breathing and other 
purposes. In addition special methods of analysis 
were developed for oxygen and moisture content of 
gases. 

A large number of research and development con¬ 
tracts were entered into with universities and indus¬ 
trial organizations to develop processes and equip¬ 
ment to meet the specific needs of the interested Serv¬ 
ices. The Army Air Forces, the Navy Bureau of 
Ships, the Navy Bureau of Aeronautics, and the 
Liaison Officers assigned to the various projects by 
these Services furnished invaluable assistance with¬ 
out which the program could not have been effective. 
Standard-type industrial processes and equipment for 
the generation of oxygen were not suitable for mili¬ 
tary needs for field generation, and development was 
entered into on all component parts of oxygen-gener¬ 
ating equipment. New methods were developed for 
oxygen production by both chemical and through 
liquefaction and distillation of air. The Summary 
Technical Report covers the detailed work of the sec¬ 
tion and points out the significant results. 

The manuscript for this volume was prepared by 
Dr. Rushton and Dr. Prentiss. The coordination 
within the Division was supervised first by Dr. Pren¬ 
tiss and later by D. Churchill, Jr. To all of these men 
the Division Chief wishes to express his sincere 
thanks. 

The Division Chief also wishes to acknowledge 
with thanks the valuable help and guidance in broad 
phases of the program and policy of Dr. Roger 
Adams, Member of the NDRC. 

H. M. Chadwell 
Chief, Division 11 

J. H. Rushton 
Chief, Section 11.1 


vii 








CONTENTS 


CHAPTER PAGE 

1 Introduction. 1 

2 Oxygen. 4 

3 Low-Pressure Cycles and Units.10 

4 High-Pressure Cycles and Units.39 

5 Air Compressors and Expansion Engines.59 

6 Oxygen Compressors and Liquid Oxygen Pumps . . 93 

7 Heat Exchange.118 

8 Liquid Air Fractionation.139 

9 Air Purification.192 

10 Miscellaneous Equipment.236 

11 Oxygen Generation from Regenerative Chemicals . . 242 

12 Oxygen Generation from Non-Regenerative Chemicals . 268 

13 Liquid Oxygen Vaporizers for Aeronautical, Medical and 

Engineering Uses.295 

14 Instruments for Testing Oxygen.309 

15 Submarine Problems.330 

Appendix.343 

Glossary.393 

Bibliography.395 

OSRD Appointees.419 

Contract Numbers.420 

Service Projects.422 

Index.423 






















Chapter i 

INTRODUCTION 

By S. S. Prentiss a 


T he activities of Section 11.1 have been con¬ 
cerned primarily with such means for generating 
and using oxygen as would be of interest to the 
military. There are three categories into which 
methods for generating and using oxygen may be 
broken down, namely, (1) the development of com¬ 
pact, lightweight, portable units for separating oxy¬ 
gen from air, (2) the development of equipment for 
supplying oxygen for specialized uses, such as air¬ 
craft breathing, and the development of instruments 
for testing oxygen intended for the specialized uses, 
(3) the generation of oxygen aboard submarines for 
use as a secondary fuel and the operation of internal 
combustion engines while the vessels are submerged. 

At the start of the war the supply of oxygen on 
foreign battle fronts was limited to that which could 
be transported as compressed gas in steel cylinders. 
It was believed that portable generators might be 
developed to supply oxygen directly for a number 
of uses. Some manufacturers bad already developed 
portable generators, but much remained to be done 
to reduce the weight and bulk of these generators and, 
at the same time, to increase the efficiency and con¬ 
venience of operation of such units at advance bases. 
Improvements were sought in methods based upon 
fractionation of air and chemical absorbents for at¬ 
mospheric oxygen. 

Section 11.1 made a detailed survey of liquid 
air cycles and equipment for the separation of at¬ 
mospheric oxygen, and decided to develop several 
alternative forms of apparatus for generating oxygen 
and charging cylinders at advance bases. The choice 
of the cycles and the direction which the development 
took was dictated by (1) expected military advan¬ 
tages of certain types of apparatus, and (2) availa¬ 
bility of equipment or successful development of 
more appropriate machinery. Since it was difficult 
to weigh these factors in advance of experimental 
work, it was decided to build several units embody¬ 
ing competing ideas. The Linde system utilizing 
high-pressure air was attractive because of the small 
size and simplicity of high-pressure equipment. Low- 
pressure systems were attractive because they offered 


a Technical Aide, Division 11, NDRC. 


a means for eliminating chemicals for air cleanup, 
and because they used more reliable low-pressure 
compressors which might also prove to be space 
saving. 

An effort was made to develop a small unit that 
might be operated directly upon large aircraft to 
give a supply of breathing oxygen to the crew, and 
replace thereby the cylinders of compressed oxygen 
which are normally carried. Although no aircraft 
unit was developed that compared favorably with 
cylinder oxygen, considerable success was had in 
developing a small unit for ground operation which 
was extremely compact and lightweight. 

A unit was developed for operation with air com¬ 
pressor equipment available on submarines, which 
might be operated for brief periods, while the sub¬ 
marine is surfaced, to generate a supply of liquid oxy¬ 
gen subsequently to be used to replenish the oxygen 
of the atmosphere in order to prolong periods of 
submergence. Some of the features of this unit made 
it attractive for a trailer-mounted generator. 

Some of the generators previously mentioned 
were redesigned to permit transportation by air and 
operation at air bases. Still others were redesigned 
for operation on shipboard. 

A requirement of the Navy for a fuel oxygen 
on submarines led to the development of a unit of 
extreme compactness for the generation of large 
quantities of liquid oxygen aboard submarines. Oxy¬ 
gen was to be generated while the submarine was 
surfaced, and used as a secondary fuel in internal 
combustion engines for submerged operations. Two 
types of units were developed in pilot-plant size, 
each producing approximately 400 pounds of liquid 
oxygen per hour. The first of these operated with 
low-pressure air, giving a unit which could operate 
with the most compact type of centrifugal air com¬ 
pressors. A second unit using medium-pressure air 
supply was operated but was found to be less advan¬ 
tageous. 

Much effort was devoted to detailed study of types 
of equipment applicable to the specialized require¬ 
ments of the different units. Air compressors and 
expansion engines normally used in commercial 
plants and available on the market were all low- 


1 



2 


INTRODUCTION 


speed, extremely heavy and bulky, and thus not eas¬ 
ily adapted to portable units. High-speed air com¬ 
pressors were developed from aircraft engine chas¬ 
sis, resulting in compactness and lightweight which 
were essential for portability. Improved expansion 
engines were developed which would operate at ex¬ 
tremely low temperatures without lubricants. 

A lightweight oxygen compressor was also devel¬ 
oped which could be used without water lubrication 
and thus avoid the necessity of redrying oxygen after 
compression. 

Liquid oxygen pumps were developed which, when 
associated with suitable heat exchanger equipment, 
could be used to charge high-pressure cylinders di¬ 
rectly from liquid oxygen. One type coidd be asso¬ 
ciated with the rectification column and heat ex¬ 
changer of an oxygen-generating unit for delivery 
of the oxygen product at a pressure suitable for 
charging cylinders. A second type operated manu¬ 
ally with an external supply of liquid oxygen. 

Heat exchanger equipment of both exchanger and 
regenerator (heat reservoir) types was critically 
studied and developed. The most important was a 
multi-pass construction suited for the deposition of 
water vapor and carbon dioxide, which combines the 
functions of exchanging heat between the different 
streams of gases in the system and removing con¬ 
densable impurities from the air stream. This is 
brought about by periodically alternating the gas 
streams between two or more channels in the heat 
exchanger, so that the impurities condensed from 
the incoming air will be re-evaporated and removed 
by the effluent nitrogen. 

In all of the generating units under consideration, 
a limitation was placed on the height of the fraction¬ 
ation column necessitating the development of col¬ 
umns with a high efficiency per unit of height. Col¬ 
umns of both the tray type and the packing type were 
studied. For units to be used on shipboard there 
was a further requirement that trays should give 
results independent of the pitching and rolling of 
the vessel. Several approaches were made to the 
problem: (1) transverse baffles were inserted in 
bubble cap trays, (2) the packing of the column was 
caused to rotate slowly, thus avoiding not only the 
effects of roll and pitch but also any permanent de¬ 
flection of the column from the vertical, (3) special 
packings were designed to distribute reflux liquid, 
and (4) further improvements were made in the effi¬ 
ciency of the column for unit height, providing suf¬ 
ficient margin of operation. 


A study was made of the injurious effects upon 
oxygen-generating equipment, of water vapor, car¬ 
bon dioxide, and combustible impurities from air, and 
of the means for their removal. These include the 
use of caustic absorbents, such as potassium hydrox¬ 
ide, Sodalime, Barylyme, and of other products re¬ 
cently placed on the market, the use of regenerable 
absorbents such as activated carhon and activated 
alumina, the deposition of the impurities on cold sur¬ 
faces as described above under heat exchangers, and 
the filtration of impurities from liquid air streams. 

In addition to the development of mechanical 
means, the possibility was examined of a unit based 
on organic chelate compounds known experimentally 
to be capable of reversibly absorbing atmospheric 
oxygen. A large-scale source of this material was 
developed, and portable units for separating oxygen 
from the atmosphere were designed. It was soon 
found that truck-mounted chemical units could not 
compete with the liquefaction units in weight and fuel 
requirements. A unit of this type for operation on 
shipboard was, however, developed and tested exten¬ 
sively for cutting and welding oxygen supply. 

Several systems for generating oxygen from chem¬ 
icals were studied. An apparatus was developed for 
generating oxygen from sodium peroxide and potas¬ 
sium tetroxide on a demand basis, suitable for use 
in the field for cutting and welding operations, medi¬ 
cal therapy, etc. In association with other groups, 
Section 11.1 developed a sodium chlorate composi¬ 
tion, possessing good storage characteristics, and an 
apparatus for supplying breathing oxygen, for emer¬ 
gency use on aircraft, to be operated with standard 
demand mask equipment. Improvements were also 
made in “rebreathers” for aircraft, making them 
available for emergency use at low temperature; 
these rebreathers combine potassium tetroxide as a 
rebreather agent with sodium chlorate composition 
as a priming agent. 

For full utilization of savings in weight and vol¬ 
ume, a system for storing oxygen as liquid rather 
than as compressed gas was developed together with 
means for converting the liquid to gaseous oxygen 
when necessary for use on aircraft, in medical ther¬ 
apy, and in engineering applications. Most attention 
was given to the development of large liquid oxygen 
vaporizers, for use on bombers and transport aircraft, 
to supply crew members and other personnel with 
breathing oxygen. Small individual units for walk- 
around use were also developed which compared 
very favorably with compressed gas systems. 




INTRODUCTION 


3 


An instrument was developed for determining the 
partial pressure of oxygen in a mixture of gases. It 
had a number of other uses, including that of deter¬ 
mining the purity of generated oxygen, the percent¬ 
age of oxygen in breathing gases such as are used at 
high altitudes, in medical therapy, and on submarines, 
and the concentration of oxygen mixed with com¬ 
bustible gases. 

Water vapor in concentrations of more than 
0.02 mg/1 in oxygen intended for aviation use con¬ 
stitutes a sufficient hazard at low temperature to make 
it desirable to determine the moisture content of 
large numbers of cylinders. A simple, convenient 
test which required but a small gas sample was de¬ 
vised. This led to refinements in the frost point 
method and to the development of a chemical indi¬ 
cator based on color change. The frost point appa¬ 
ratus seemed to solve this problem satisfactorily, but 


the chemical methods were never developed suffi¬ 
ciently, in point of view of reproducibility and stor¬ 
age characteristics, to be useful as a procedure for 
field instrument operation. 

A combined vapor pressure and gas thermometer 
was developed to cover the entire range from ambient 
temperatures to the boiling point of oxygen. 

A detailed study was made of the operation of 
diesel engines on closed cycles (under submerged 
conditions) with dilution of the combustible agents 
of fuel and oxygen with exhaust gases rather than 
atmospheric nitrogen. There was, further, the prob¬ 
lem of disposing of exhaust gases from a submerged 
submarine, in such a way that it would not appre¬ 
ciably contribute to the vessel’s being visibly detected. 
Means were developed for dispersing the exhaust 
gas as very fine gas clouds which would be quickly 
dissolved in sea water. 



Chapter 2 

OXYGEN 

By J. H. Rushton 


21 CYCLES AND EQUIPMENT FOR 
THE MECHANICAL SEPARATION 
OF OXYGEN FROM AIR 

211 Oxygen Production Units for 
Military Purposes 

I n the latter part of 1941 it became apparent 
that there was a military need for equipment to 
produce oxygen on naval vessels and at advanced 
military land bases. Military requirements were sum¬ 
marized at a meeting in January, 1942. 1 The Navy 
suggested three types of plants for oxygen produc¬ 
tion. 

1. A unit to be operated on shipboard to produce 
approximately 600 cfh of high purity oxygen deliv¬ 
erable at about 150 psi for use in cutting and weld¬ 
ing. 

2. A plant for the production of up to two tons 
of 95 % liquid oxygen per hour. This large plant was 
to be developed from a smaller pilot plant built to 
obtain necessary engineering information. The im¬ 
mediate interest was therefore centered in a pilot 
plant for the production of about 400 pounds of 95% 
liquid oxygen per hour. 

3. A small liquid oxygen plant to supply breathing 
oxygen for submarine use. This plant to produce 
about 35 lb of liquid oxygen per hour at purity of 
at least 95%. 

The Army was interested in three other types of 
plants for oxygen production. 

1. A mobile gaseous oxygen plant to produce 1,000 
cfh of high purity (99.5%) oxygen for breathing 
purposes. This oxygen to be compressed to about 
2,000 psi. 

2. A unit transportable by air with a capacity of 
at least 400 cfh of breathing oxygen compressed to 
2,000 psi. 

3. An airborne unit to operate in a plane while in 
flight, to have a capacity of about 120 cfh (standard 
temperature and pressure) of high purity breathing 
oxygen for delivery at pressures above 10 psi. 

In 1942 the Army had available for procurement 
large trailer plants weighing approximately 34,000 
lb which could be used for mobile oxygen supply. 


The Navy had nothing in sight to fulfill their re¬ 
quirements. Accordingly, the NDRC program was 
extended in scope to try to fulfill all the requirements 
of the Services. 

A complete survey was made of the many pro¬ 
posed cycles for the production of oxygen from air. 
This section of the report concerns those cycles 
which are primarily mechanical in operation. They 
all involve the compression of air, its liquefaction, 
followed by rectification, and, finally, by compression 
of the resulting oxygen. Other means for producing 
oxygen to satisfy military requirements are covered 
in Chapters 11 and 12. 

2. 2 TYPES OF CYCLES 

Fundamentally there are only two types of cycles 
in use: the Linde and the Claude cycles, but there 
are many variants of these. 

2 21 The Linde Cycle 

This cycle is illustrated diagrammatically in Fig¬ 
ure 1. The high-pressure air is cooled by heat ex¬ 
change with the outgoing streams of oxygen and 
waste nitrogen, expanded through a valve to an 
intermediate pressure, condensed in the reboiler of 
the tower by the boiling oxygen, throttled to the 
tower pressure, and introduced to the tower as liquid 
reflux. The refrigeration is supplied in the cooler, 
and the cooling obtained by the large temperature 
drop which accompanies the expansion through the 
first valve. Often this system is supplemented by a 
low-level refrigeration, or forecooling step before 
expansion of the high-pressure air. In this cycle the 
bead pressure is maintained at least as high as 600 
to 700 psi, and frequently as high as 3,000 psi. 

2 2 2 The Claude Cycle 

This cycle is also illustrated in Figure 1. In this 
system the refrigeration is supplied by allowing the 
air to do work in an expansion engine. The air pres¬ 
sure used may vary from 60 psi to 3,000 psi. When 
the head pressure is low, as in the M-7 unit, the air 
after expansion in the engine is at such a low pres¬ 
sure that it cannot be condensed by the boiling oxy- 


4 


TYPES OF CYCLES 


5 




Figure 1. The Linde cycle and the Claude cycle. 


gen and is therefore not available as liquid reflux. 
This expanded air may either be returned imme¬ 
diately to the heat exchanger, or it may be used to 
aid the fractionation process, as shown in the sketch. 
There is also a variation of this cycle in which the 
expansion is to a pressure high enough so that the 
exhaust may be condensed and used as liquid reflux. 

2 2 3 Other Cycles 

Exhaustive study was made of a number of modi¬ 
fications of the two cycles shown in Figure 1 to eval¬ 
uate relative advantages and possibilities. Ten rather 
distinctive variations are shown in Figures 2 to 11 
and they cover the basic processes to which practi¬ 
cally all known mechanical cycles for oxygen pro¬ 
duction are related. Each figure is labeled to show 
the particular characteristic of the cycle. Complete 
thermodynamic analyses were made, and engineer¬ 
ing considerations necessary to build plants on a 
reasonably large scale were studied. In particular, 
the size and weight of compressors, expanders, air 
clean-up systems for the removal of carbon dioxide, 
dryers, heat exchangers, and rectifying columns were 
carefully investigated. On the basis of these sum¬ 
maries and refrigeration requirements, certain cycles 


were found to offer great advantages in compactness 
and ease of air clean-up, providing suitable compres¬ 
sion equipment could be made available. These stud¬ 
ies were summarized in reports which give complete 
details on the methods of calculation used. 2,3,4 ’ 7 ’ 8 

Military requirements indicated the need for both 
very small and very large plants. The small plants 
were to be as light in weight as possible, of minimum 
height and to require small floor space and volume, 
at the expense (if necessary) of high fuel economy. 
The smallest plants were to he very easily transport¬ 
able, but larger plants of approximately 1,000 cfh 
were to be capable of installation on lightweight 
trailers. The large stationary plants were to have 
moderate weight with small floor space and were to 
require very low power consumption. For all plants 
it was felt that great emphasis should be placed upon 
simplicity of operation and the elimination, so far 
as possible, of chemical supplies for the removal of 
carbon dioxide and water from the air to be processed. 

An examination of equipment weights and sizes 
necessary for small oxygen production plants showed 
that there was great room for improvement in es¬ 
sential items, such as compressors and air clean-up 
equipment; that development of lightweight units 




























































6 


OXYGEN 


AIR IN COOLING 



COOLING 



Figure 4. Joule-Thomson cooling and expansion engine 
with high temperature intake. 


AIR IN 


COOLING 



Figure 3. Joule-Thomson cooling with auxiliary refrig¬ 
eration. 


air in cooling 



Figure 5. Joule-Thomson cooling and expansion engine 
with low temperature intake. 




























































































































































































































TYPES OF CYCLES 


7 


AIR IN COOLING 




FigureS. Refrigeration by three-stage helium expan¬ 
sion. 


AIR IN COOLING 



AIR IN WATER WATER HELIUM 



Figure 7. Expansion engine with low temperature in- Figure 9. Single-stage helium expansion refrigeration 

take regenerative heat exchangers. applied to column. 




























































































































































































































































































8 


OXYGEN 



Figure 10. Single-stage helium expansion refrigeration 
applied to exchanger. 


would probably be feasible, and that research and 
mechanical development to this end could be justi¬ 
fied. 4 

The cycles of greatest potential value to the serv¬ 
ices were grouped into those involving low-pressure 
air supply (up to 150 psi) and those involving inter¬ 
mediate (600 psi) and high-pressure (up to 3,000 
psi) air supply. In all cases, equipment for the com¬ 
ponent parts of the cycles were evaluated with regard 
to procurability, operating characteristics, and weight. 
For almost every item of equipment a program of 
research and development was initiated to produce 
the lightest and most compact unit. 5 ’ 6 Individual 
types of equipment such as compressors, heat ex¬ 
changers, etc., will be described under separate head¬ 
ings and will follow a description of the cycles and 
units which seemed to offer the best possibilities for 
achieving the military requirements. 

2 3 EQUIPMENT DEVELOPED IN 
THE OXYGEN PROGRAM 

In Chapters 3 and 4 several cycles for the mechani¬ 
cal separation of oxygen from air are discussed, 
and operating units are described together with de¬ 
tails as to size and operating characteristics. Since 


CASCADE TYPE, JOULE-THOMSON COOLING 



Figure 11. Expansion engine with low temperature in¬ 
take recuperative heat exchangers. 


military requirements emphasized the need for com¬ 
pactness, simplicity, lightness in weight and minimum 
height, together with dependability and ease of main¬ 
tenance but not necessarily coupled with the high 
efficiency required in industrial operations, it was 
necessary to investigate the design of all component 
parts of equipment used in the separation of oxygen 
from air by mechanical means. To obtain the de¬ 
sired compactness and mobility it was necessary to 
investigate the possibility of developing very light¬ 
weight equipment. Further, the thermodynamic ef¬ 
ficiency of the component parts had to be as high as 
possible. In so far as possible the aim was to de¬ 
velop equipment which would require an absolute 
minimum of chemical supplies other than fuel and 
lubricants. Plants were developed and built which 
used other chemical supplies but the reasons for this 
were twofold: First, because the use of chemicals 
for air cleanup was a customary operation, and its 
success was assured. Therefore, cycles were used 
depending upon chemical cleanup so that there 
would be a greater chance of developing a useful unit 
if the other processes, wherein chemicals were not 
required, should prove to be failures. Second, it 




















































































































































EQUIPMENT DEVELOPED IN THE OXYGEN PROGRAM 


9 


might well develop that processes in which chemicals 
were not required for air clean-up would become 
too complicated and too sensitive in operation for 
successful military application and that it might, in 
the end, become more practicable to set up a service 
supply of chemicals than to have less dependable 
equipment in tbe field. 

There are a number of operations which are the 
same in all the processes mentioned before. For 
example, air compressors, heat exchangers, reboilers, 
and fractionating columns are common to all me¬ 
chanical processes. A study was made of the equip¬ 
ment available for each of the operations for all of 
the cycles investigated. As a result it was decided 
to initiate experimentation and development on the 


performance and construction of most of the com¬ 
ponent parts of the plants under consideration. Con¬ 
siderable success was achieved in the development of 
compact lightweight equipment. A great deal of in¬ 
formation has been obtained on the performance of 
various types of heat exchangers and fractionating 
columns. Considerable experimental data have been 
obtained on the thermodynamic properties of air and 
the impurities in air such as carbon dioxide and 
acetylene, and these data have already been made use 
of in the development of plants, and will, no doubt, 
be of considerable use in the future. The great 
amount of experimental data and equipment develop¬ 
ment will be summarized briefly in the following 
chapters. 



Chapter 3 

LOW-PRESSURE CYCLES AND UNITS 

By /. H. Rushton 


31 THE COLLINS AIRBORNE UNIT 

C ycles for oxygen production operating at low 
pressure offered great possibilities for the use of 
compact lightweight equipment. A very small unit 
had been operated experimentally, using air at 150 
psi, corresponding in general principles to the cycle 
in Figure 5, Chapter 2. This unit, proposed by S. C. 
Collins, 1 ’ 4 had the distinct advantage of being able 


streams, but is also used as a mechanism for pre¬ 
cipitating water, ice, carbon dioxide, and hydrocar¬ 
bons from air. These impurities are then evaporated 
into the effluent nitrogen stream on suitable reversal 
of gas flows. The use of such heat exchangers offers 
the possibility of eliminating chemical clean-up sup¬ 
plies, and, if successful, would reduce the complexity 
of equipment of the oxygen plant. Previous to the 
operation of the Collins unit, the Linde-Frankl cycle 



to operate without the use of chemical agents for the 
removal of carbon dioxide, oil, and water, from the 
compressed air. A flow sheet of the Collins cycle 
as originally proposed is shown in Figure 1. The 
most arresting feature of this unit is the heat ex¬ 
changer. 2 The heat exchanger not only functions to 
transfer heat between air, nitrogen, and oxygen 


had been operated with considerable success in large 
plants in Germany. In the Linde-Frankl cycle, re¬ 
generators were used in place of heat exchangers, 
and water, carbon dioxide, et cetera, were depos¬ 
ited in these regenerators. The precipitated water, 
carbon dioxide, et cetera, were then evaporated by 
effluent nitrogen to which was added an additional 


10 


































































































MOBILE LOW-PRESSURE GASEOUS OXYGEN UNITS 


11 


air stream, and which, processed at high pressure, 
had been dried and cleaned by the use of chemicals. 
This additional stream, together with the effluent 
nitrogen, was sufficient to cleanse the regenerators 
and allowed the cycle to operate. The Collins heat 
exchangers offered the possibility of eliminating the 
use of the extra air stream and all the equipment and 
supplies necessary for its proper functioning. 8 Fur¬ 
ther, the Linde-Frankl cycle had been operated at 
low pressures (usually around 90 psia but on occa¬ 
sion as low as 45 psia) and it appeared feasible that 
lightweight compressors could be obtained of both 
reciprocating and rotary design for portable oxygen 
plants if pressures in the neighborhood of 100 psia 
could be proved useful for military oxygen produc- 


provided complete refrigeration for the unit. 3 ’ 5 It 
was largely upon the considerations just mentioned 
that model plants were built embodying features of 
the low-pressure and Collins cycles. 

Final development of the Collins cycle and unit is 
illustrated in Figure 2, which shows the final flow 
sheet for the production model, and Figure 3, which 
shows the unit before insulation and without air and 
oxygen compressors. The unit has been produced in 
quantity for both the Army Air Forces and the 
Navy. 5 The unit requires 25 scf per min of air at 
150 psi and produces 99 . 5 -\-% gaseous oxygen at a 
rate of 150 cu ft per hr. The unit, without air and 
oxygen compressors, weighs 165 lb and occupies a 
volume of approximately 9 cu ft. 



-INDICATES FLOW DURING STARTUP ONLY 


Figure 2. Collins final unit. 


tion. Both the Collins and the Linde-Frankl cycles 
made use of a low-temperature expansion engine. 
The Kapitza-type centrifugal expander was rumored 
to have been used in Linde-Frankl plants in Ger¬ 
many, and small reciprocating expanders were avail¬ 
able in the United States. One of the features of the 
Collins unit was its ringless piston expander which 


3 2 MOBILE LOW-PRESSURE 

GASEOUS OXYGEN UNITS 

3-2.1 Kellogg M-2 Plant 

Two lines of development were followed to de¬ 
velop a mobile 1,000 cfh high-purity gaseous oxygen 
unit. Plans were laid out for both a low-pressure 



















































































































































12 


LOW-PRESSURE CYCLES AND UNITS 



Figure 3. Aircraft oxygen generator. 


and a high-pressure plant (M-l). The low-pressure 
plant was to be trailer-mounted, using regenerators 
together with reciprocating expanders, and to operate 
with air pressure at 105 psia. 11 This was designated 


as the M-2 unit and the flow sheet for it is shown 
in Figure 4. The unit was operated briefly hut not 
very successfully due to equipment failures. It is 
now believed that the cycle of Figure 4 would not 




















MOBILE LOW-PRESSURE GASEOUS OXYGEN UNITS 


13 


PREFRACTIONATOR 
E-2 



TEMPERATURE IN 
OEGREES F 


PRESSURE LBS/SQ 
IN GA 

7 GAS FLOW DRY 
SCFH 

PURITY % 02 


AIR FILTER 


Figure 4. M. W. Kellogg Co. design conditions for 1,000 cfh mobile oxygen unit, LP system unit M-2. 


allow continuous operation for extended periods of 
time. Slight modification of the cycle to allow proper 
cold-end temperature approach at the regenerators 
would probably make tbe cycle operable. Plans were 


made to test this point but the pressure of other mat¬ 
ters has made it impossible to do so. Details regard¬ 
ing tbe action of beat exchangers and regenerators 
functioning as air cleaners for the removal of carbon 






















































































































































































































































































14 


LOW-PRESSURE CYCLES AND UNITS 


dioxide, water, et cetera, will be covered in later 
chapters. Equipment and operating details of the 
M-2 unit are available. 10 ’ 11 

3 2 2 Kellogg M-7 Gaseous Oxygen Plant 

A cycle was laid out and a plant built based on the 
use of Collins reversing heat exchangers utilizing air 
at 105 psia. 9 The plant was designed for the pro¬ 
duction of 1,000 cfh of 99.5-}-% oxygen under ex¬ 
treme temperature and humidity conditions. All of 
the equipment was to be mounted on a trailer and the 
only supplies were to be gasoline, lubricating oil, and 
a small amount of water. This project was desig¬ 
nated M-7, and held that notation through all ex¬ 
perimental work. A number of units based on this 
cycle were built for the Services and for Lend- 
Lease. 13 Complete details of the M-7 development 
appear in progress and final reports; they are sum¬ 
marized elsewhere. 11 ’ 13 Details pertaining to the cycle 
are of interest because the cycle has proven to be the 
best for military production of gaseous oxygen, and 
has been modified and adapted to the production of 
liquid oxygen on a large scale. Also a high-capacity, 
lightweight, air-transportable model of the cycle has 
been procured by the Air Forces. 13 A general de¬ 
scription of the M-7 plant and its process follows. 

The M-7 unit was designed to produce 1,000 scfh 
of 99.5% gaseous oxygen under the rather extreme 
atmospheric conditions of 120 F ambient and 90 F 
dew point, and to deliver this oxygen dry (dew point 
—70 F) at 2,200 psi. L T nder more usual atmospheric 
conditions, such as 70 to 80 F ambient, the unit has 
produced 1,300 standard cfh of 99.45%' oxygen, with 
no increase in feed air capacity. If the compressor 
and engine are speeded up to deliver 15% more than 
the designed air capacity, the unit will deliver 1,500 
scf per hr of oxygen at 98.7% purity. The unit was 
designed to run continuously for periods of 120 hr 
or more. 

The refrigeration required by the unit is supplied 
by a reciprocating expander working at a head pres¬ 
sure of 100 psia. Water and carbon dioxide are re¬ 
moved by condensation and evaporation in the re¬ 
versing exchanger, and not by chemical means, thus 
making the unit independent of any chemical supply 
whatever. This is a characteristic of great importance 
in a field unit. A single tower with vapor feed is used 
for fractionation and the oxygen is compressed in 
a dry, non-lubricated compressor. A flow sheet with 
typical operating data is shown in Figure 5. 


Air Compression. Atmospheric air is filtered, then 
compressed in a two-stage, high-speed, air-cooled re¬ 
ciprocating compressor, and is cooled after each stage 
of compression directly against cooling air, any con¬ 
densate being separated out after each stage. The 
cooler is designed to cool the compressed air to 135 F 
when the ambient air is at 120 F with 90 F dew 
point. 

In the second stage, 100 psi air, after leaving the 
entrainment separator, flows through a special paper 
filter to remove any entrained oil (down to 1 micron 
drop size). It is important to remove entrained oil 
completely, because presence of oil in the air pre¬ 
vents the proper purification by the exchanger. 

Air Purification and Heat Exchange. The com¬ 
pressed, filtered air enters the parallel tubes of a 
reversing exchanger (Collins tubes) through a re¬ 
versing valve. Each reversing exchanger tube is a 
three-annulus, three-fluid exchanger in which the 
incoming air is cooled by means of the effluent oxy¬ 
gen product and waste nitrogen. The two channels 
or passages which carry the air and waste nitrogen 
are very similar in size and in flow resistance, but 
the oxygen annulus is much smaller. The coldest 
section of the exchanger (fourth tube pass) has three 
small tubes coiled around and soldered to the ex¬ 
changer, making it a four-fluid unit at this point. 
Part of the waste nitrogen flows continuously through 
these coils which are known as the “unbalance flozv” 
pass. All annuli have extended surface packing and 
are in soldered thermal contact with each other and 
with the outer tube coils. 

Though oxygen flows continuously through its 
passage, the operation of the reversing valve causes 
air and waste nitrogen to be diverted periodically 
from one of the two passages to the other, and, as a 
result, waste nitrogen flows at all times through a 
passage which had carried feed air during the pre¬ 
vious part of the cycle. The switching of these two 
streams results in the purification function of the 
exchanger. Thus, in one half-cycle, when air is being 
cooled, first water ice and then carbon dioxide snow 
are precipitated from the air and are deposited on 
the metal surface. Before this process has continued 
to the point where the surface has become seriously 
fouled, tbe reversing valve causes the waste nitro¬ 
gen to stream through the impurity-laden channel. 
Though the waste nitrogen is colder than the air, the 
fact that its total pressure is much lower enables it 
to evaporate tbe impurities which are lodged on the 
surface as a result of the passage of air in the pre- 



1 



































































































































































































































































































MOBILE LOW-PRESSURE GASEOUS OXYGEN UNITS 


15 


vious half-cycle. The evaporated impurities are then 
carried out of the system by the waste nitrogen, and 
the unit can therefore operate continuously without 
chemical purification of the feed air. 

The water impurities deposit at the warm end of 
the exchanger, where the normal relationship be¬ 
tween pressure and temperature of the two switching 
streams is satisfactory for proper evaporation of the 
water ice. The carbon dioxide, on the other hand, 
precipitates at the cold end of the exchanger and in 
this region normal conditions of temperature and 
pressure do not suffice to insure evaporation of the 
carbon dioxide. A fourth heat exchange passage 
(called the unbalanced flow pass) is therefore pro¬ 
vided in the coldest part of the exchanger. Part of 
the waste nitrogen flows through this fourth channel 
continuously before entering either one of the two 
reversing annuli of the reversing exchanger. By 
means of this continuous flow, the temperature re¬ 
lationships are sufficiently changed and controlled 
so that evaporation of carbon dioxide is satisfactory 
for prolonged operation. 7,8 This fourth passage con¬ 
sists of three parallel coils of small tubing wrapped 
around the coldest portion of the reversing ex¬ 
changer. 

Refrigeration. The purified air, after being cooled 
in the reversing exchanger, leaves through a system 
of check valves which operate in response to the re¬ 
versing valve at the warm end of the exchanger. 
From the check valve manifold the feed air flows to 
a high-pressure surge drum, and from the surge 
drum, part of it (roughly 23%) flows to the expander 
where it performs external work and generates all 
the refrigeration required by the plant. The ex¬ 
panded air flows through a second surge drum and 
then to the tower as vapor feed, below the sixth tray. 

The remainder of the air from the high-pressure 
surge drum (about 75%) flows to the liquefier ex¬ 
changer, which is a two-fluid, steady flow exchanger, 
where it is further cooled and partially condensed. 
This portion of air then enters the condenser in the 
tower reboiler where it is condensed to liquid. It is 
then filtered through a glass cloth filter and throttled 
into the tower as reflux below the first tray from the 
top. 

Fractionation System. The fractionation tower con¬ 
sists of a single column fed with liquid air and with 
expanded air (vapor feed). A single column requires 
considerably less height than a double column, and 
low height has been a controlling military require¬ 
ment. The expander discharge, at a pressure too low 


to be condensed in the reboiler of the tower, is fed 
to an intermediate point of the column as vapor. 
Low-pressure air cannot be condensed in the re¬ 
boiler nor be fractionated by itself; however, the in¬ 
troduction of the vapor feed to the low-pressure 
tower is beneficial, because it allows a greater re¬ 
covery of oxygen from the high-pressure liquid feed 
than is theoretically possible in a simple single col¬ 
umn without vapor feed. Thus the advantage of 
vapor feed is that single-column performance can 
be surpassed, and double-column performance ap¬ 
proached while maintaining the simplicity of a single 
liquid expansion valve. 

The tower has a dry tray at the top as an entrain¬ 
ment separator, and a special oxygen draw-off tube 
below the bottom tray to minimize entrainment in the 
oxygen below the bottom tray. 

Most of the waste nitrogen overhead flows through 
the liquefier exchanger, and the remainder through 
the fourth channel at the cold end of the reversing 
exchanger, and then through the check valves into 
the reversing exchanger and out of the reversing 
exchanger through the reversing valve to the atmos¬ 
phere. 

The oxygen, after leaving the tower, flows through 
the reversing exchanger, by-passing the liquefier. 
Since oxygen flows continuously through its annulus, 
which is not contaminated by air, water, or carbon 
dioxide, the oxygen produced is pure and dry. 

Oxygen Compression. The oxygen from the re¬ 
versing exchanger flows through a surge drum into 
the oxygen compressor, which is a four-stage, dry, 
non-lubricated, water-cooled reciprocating machine. 
After each stage of compression the oxygen is filtered 
through porous stone to remove carbon dust from the 
rings, and is then cooled by an air-cooled heat ex¬ 
changer against a blast of cooling air. The com¬ 
pressed oxygen is charged to cylinders at 2,200 psi 
as final product, and is perfectly dry and suitable for 
aircraft breathing since no water for lubrication of 
the compressor is required. 

Miscellaneous. The energy of the expander is ab¬ 
sorbed by means of a built-in, water-cooled air com¬ 
pressor. This water-cooling duty and the water¬ 
cooling duty for the oxygen compressor are effected 
directly by cooling air. Oil-cooling for the engines 
and compressors is supplied by air-cooled units built 
into the machines. 

A supply of hot, clean air, for use in thawing out 
the plant as occasion requires, is made available by 
the air heater exchanger. In this unit air which has 



16 


LOW-PRESSURE CYCLES AND UNITS 



0 200 400 600 800 1000 1200 1400 

OXYGEN PRODUCTION, SCFH 

Figure 6. Production of M. W. Kellogg low-pressure 

oxygen unit M-7. 

been compressed, cooled, freed of entrainment, and 
filtered is then heated by means of the hot air dis¬ 
charged from the second stage of the compressor. 

Control. The M-7 low-pressure unit has five proc¬ 
ess control valves. The expander control valve CV-1 
(Figure 5) is located on the brake compressor dis¬ 
charge line, and is manipulated in order to control 
the expander speed and therefore the refrigeration 
balance of the unit. When the liquid level tends to 
drop, this CV-1 valve must he opened somewhat in 
order to speed the expander and build hack the liquid 
level. 

The reflux valve CV-2 throttles liquid air into the 
top of the column, and is used to control the head 
pressure at which the unit operates. This is possible 
because the tower is equipped with a forced-feed 
reboiler, and when the CV-2 reflux valve is closed, 
liquid builds up in the condenser tubes. The con¬ 
sequent partial blanking of the condensing surface 
causes the head pressure to rise so that condensation 
may proceed on the smaller surface. 

The unbalance control valve CV-3 is set in the 
waste gas line, feeding the reversing exchanger at a 
point between the connections to the fourth or “un¬ 
balance flow” passage at the cold end of the revers¬ 
ing exchanger. When this valve is closed, part of 
the waste gas is circulated through the unbalance 
coil and in this manner produces a reduction in the 
temperature approach between the two reversing 
streams, thus improving conditions for evaporation 
of carbon dioxide. Tbe cold end approach is usually 
maintained at 5 to 8 F, and this CV-3 valve must 
be closed sufficiently to accomplish this. 

Tbe oxygen draw-off valve CV-4 is on the oxygen 


line downstream of the (warm) reversing valve, and 
is used to control the purity of the oxygen indirectly 
by controlling the total quantity of oxygen with¬ 
drawn. For maximum production, this draw-off 
valve is opened as much as possible without incur¬ 
ring a loss in purity. 

The liquefier by-pass valve CV-5 is used to control 
the reversing exchanger outlet air temperature. As 
this valve is opened, colder waste gas is sent to the 
reversing exchanger, and thus its outlet temperature 
is dropped. The outlet temperature should be cold 
enough so that the bulk of tbe carbon dioxide is 
trapped out in the reversing exchanger, but at the 
same time not so cold as to produce liquefaction in 
the expander. 

Of these five control valves, the reflux valve CV-2 
is the only one that may require frequent attention, 
and this is probably due to partial plugs caused by 
residual carbon dioxide in tbe stream. The CV-1 
expander control valve setting needs attention in 
order to control the liquid level should there be a 
change in atmospheric conditions. The remaining 
three valves, however, require no attention after the 
unit has been brought to a steady operating condition 
and the settings have once been made. This is re¬ 
flected in the very steady operation of the unit and 
the complete absence of any periodic variation in 
pressures or temperatures in the plant. This steadi¬ 
ness of operating conditions is reflected in the ease 
with which the unit can be operated very successfully 
by personnel with no process or engineering back¬ 
ground at all. 

Performance Data. The gaseous oxygen produc¬ 
tion of the unit in its final form is illustrated in 
Figures 6 and 7. Figure 6 shows production at a 
total air flow of 12,000 scfh air, which was used in 
most tests. The general shape of the curve is drawn 
with some consideration for measurements taken on 














EF 

PL 

FECT OF TOTAL 
RITY AT A CONST 

_ 

'EED ON OXYGEN 
ANT YIELD OF 1011 

L_ 

' 


98- 1 - 1 - 1 - 

11000 12000 13000 14000 15000 

FEED RATE. SCFH 


Figure 7. Liquid air fractionation portable oxygen unit 
M-7, run 22. 




























Figure 8. Model LP-1 flow diagram. 
































































































































































































































































































MOBILE LOW-PRESSURE GASEOUS OXYGEN UNITS 


17 


the unit before all the final changes were made. Fig¬ 
ure 7 shows the effect of increasing the total air feed 
to the unit. The tests summarized in these two charts 
were made with an inlet air temperature of 60 to 
80 F. The following tabulation gives the results of 
tests made with feed air saturated with water at 
135 F (equivalent to 120 F ambient air). 

1 he tests on the M-7 unit were made almost ex¬ 
clusively with plant air. The performance of an in¬ 
tegrated unit can be derived from these tests on the 
basis of the specified compressor suction volume of 
13,200 cfh. At design atmospheric conditions of 
120 F ambient and 90 F, the mobile compressor of 
13,200 cfh suction volume would deliver 11,200 
standard (60 F, 30 in. Hg) cfh of dry air, and from 
Table 1 it can be seen that 1,000 scfh of 99.4% oxy¬ 
gen were produced at this air flow. This comes quite 
close to the design condition of 1,000 scfh of 99.5% 
oxygen at 120 F ambient, 90 F dew point. At more 
normal atmospheric conditions, such as have been 
used in testing the bulk of the units developed for 
the Services, the compressor delivery would rise to 
some 13,000 scfh of dry air from which, as shown in 
Figure 7, the M-7 unit produced 1,300 scfh of 
99.45% oxygen (or 1,290 scfh of 99.5% oxygen). 
If the compressor could be speeded up to deliver 
15,000 scfh, the cold box could deliver 1,500 scfh of 
98.7% oxygen. 


Table 1 


Inlet temp. 

F 

Air feed 
scfh 

Production 
scfh 6, 

Purity 

% o 2 

135 

10,000 

840 

99.7 

135 

10,500 

1,000 

99.2 

135 

11,000 

1,000 

99.4 

135 

11,300 

1,000 

99.2 

135 

12,000 

1,000 

99.7 

138 

14,000 

1,180 

99.6 


It is of interest to note the large effect of extreme 
ambient conditions on production, namely, that 
though M-7 should be classified as a 1,000 scfh unit 
for extremely hot, humid climates, its classification 
would be 1,250 scfh for more usual atmospheric con¬ 
ditions. This difference in capacity is due to air 
delivery from the compressor, and is not due to 
the refrigeration cycle employed. 

The M-7 unit was also run to make liquid oxygen. 
This was done by speeding up the expander to 300 
to 350 rpm and allowing the liquid level to build up 
in the reboiler. When the level reached 12 to 13 in., 
liquid was drained off and weighed. The liquid pro¬ 


duced in this manner was 17 lb per hr (equivalent 
to 200 scfh gas). In order to keep the purity from 
becoming too high some 500 scfh of gaseous oxvgen 
were also withdrawn while liquid oxygen was being 
made. 

Production Model of M-7 Unit 

A flow sheet of the final production model (desig¬ 
nated LP-1) is given in Figure 8. The LP units 
differed only slightly from the M-7. All the differ¬ 
ences had to do with arrangement of equipment to 
conform to service' desires and to allow maximum 
simplicity for production-line assembly. 13 Figure 9 
is a picture of the trailer assembly which houses the 
complete oxygen plant. Figure 10 shows the plan 



Figure 9. Clark mobile oxygen generating unit, Model 
LP-1. 


view of the arrangement of equipment and Figure 11 
shows several elevation group sections. The total 
weight of the LP-1 unit complete trailer mounted was 
22,000 lb. Details of the equipment in this production 
model are summarized as follows. 

Engine. Power for all moving equipment is sup¬ 
plied by a Lycoming 6-cylinder, air-cooled, modified 
aircraft engine through a rugged V-belt drive. The 
engine is flexibly coupled to a shaft bearing the main 
9-in. diameter, 15-groove sheave. Both ends of the 
shaft are supported in self-aligning roller bearings. 
Normal operating speed is 2,400 rpm. 

Dri-Air Compressor. The air compressor is a 6- 
cylinder, horizontally opposed, two-stage, air-cooled 
machine having six 5)4-in. bore and 3^s-in. stroke, 
single-acting compressor cylinders (see Chapter 5), 
This machine is flexibly coupled to a shaft and sheave 
assembly supported at both ends by a self-aligning 

















18 


LOW-PRESSURE CYCLES AND UNITS 



DOOR 



Figure 10. Elevation views of Clark LP-1 unit. 












































































































































































































































































































































































































































































MOBILE LOW-PRESSURE GASEOUS OXYGEN UNITS 


19 


O 




Figure 11. Clark LP-1 unit, elevation and plan views. 


roller bearing. Power is supplied to this shaft by the 
engine drive shaft through 15 belts. The compressor, 
which operates at 1,600 rpm, is novel in that it uti¬ 
lizes Graphitar piston rings and packing rings, conse¬ 
quently requiring no lubricating and thus eliminating 
oil droplets from the air stream (see Chapter 5). 


Coolers. The compressed air is cooled between 
stages directly against air in a radiator made of ^-in. 
OD Rome Turney finned tubes. Cooling air is sup¬ 
plied by an axial flow, 16-blade fan built into the road 
side of the trailer. The fan is driven by V belts from 
the air compressor shaft. The intercooler is designed 





























































































































































































































































































































































































































20 


LOW-PRESSURE CYCLES AND UNITS 


to cool all the compressed air and oxygen to a ter¬ 
minal temperature of 135 F when the ambient tem¬ 
perature is 120 F. The intercooler, besides having 
two air sections and four oxygen sections, carries 
a coil to provide cooling for the water circulating 
system. The water circulating pump takes its power 
from the air compressor auxiliary drive. Figure 12 is 
a picture showing the arrangement of the engine 
room on the trailer. 


annuli, while oxygen flows continuously through the 
innermost annulus. 

The liquefier consists of one 4*4-in. OD internally 
packed, Collins triple annulus exchanger tube having 
an effective packing length of 5 ft 5 J4 in. The cold, 
low-pressure nitrogen flows continuously through 
the three annuli while high-pressure air flows through 
a series of spiral-wound OD copper tubes 

wound around the outside of the 4*4-in. exchanger 



- -rspws——• 


WATER TANK 

X — r — 




WATER FLOW 
I NDICATOR 


ENGINE 
PANEL BOARD 


r ©> 

\ 

ENGINE 1 


OXYGEN 

PORO-STONE 

FILTERS 


AIR FILTER 


LYCOMIN G 
ENGINE 


HIGH PRESSURE 
AIR SURGE DRUM 


EXHAUST 

MANIFOLD 


CLARK DRI OXYGEN 
COMPRESSOR 


Figure 12. Engine room, through front door. 


Heat Exchangers. The reversing exchanger con¬ 
sists of twenty-four 3^-in. OD internally packed, 
Collins triple annulus exchanger tubes having effec¬ 
tive packing lengths of from 4 ft 4*4 in. to 5 ft 3*4 in. 
(see Chapter 7). The tubes are arranged in six paral¬ 
lel rows of four tubes each, in series, so that an effec¬ 
tive exchanger length of 19 ft 4 in. results. Air and 
waste nitrogen are alternately passed by two outer 


tube. Figure 13 is a picture of the cold box. The cold 
box is that part of the unit in which is placed all of 
the equipment handled at very low temperatures. The 
arrangements of heat exchangers and their manifolds 
is illustrated. Figure 14 is another picture of the 
cold box showing the heat exchangers on the right, 
the liquefier having a copper tube wrapped about it 
spirally, and the fractionating column at the front. 

























MOBILE LOW-PRESSURE GASEOUS OXYGEN UNITS 


21 



Figure 13. Assembly view Model LP-1 cold box. 






















































iVlkST- 


22 


LOW-PRESSURE CYCLES AND UNITS 



Figure 14. Assembly view Model LP-1 cold box. 






















































MOBILE LOW-PRESSURE GASEOUS OXYGEN UNITS 


23 


Expansion Engines. The expansion engines are 
2-cylinder, vertical machines having 4-in. bore and 
35 ' 2 -in. stroke (see Chapter 5). The expansion engine 
pistons are ringless, lap-fitted nitralloy operating in 
hardened nitralloy cylinders. These cylinders are 
surrounded by glass-wool insulation. Each crosshead 
of the machine is an integral compressor cylinder to 
absorb energy generated in the expansion end of the 
unit. Power is supplied for these machines by the 
expansion of the high-pressure air. 

To provide ultimate safety in the operation of the 
dry oxygen compressor and to insure against losses 
in the expansion engine, circulating cooling water 
is employed to cool the oxygen compressor and the 
packing glands and heads of the expansion engine 
compressor. 

All low-temperature piping is made up of Mueller 
Brass Company, or equivalent, solder fittings and 
copper tubing. 

Fractionating Column. The fractionating column 
is a 29-tray rectangular bubble-cap, 12-in. diameter 
tower approximately 6 ft tall (see Chapter 8). Spac¬ 
ing between trays is 2 in. Vapor feed is provided for, 
five trays from the top. A glass cloth filtering medium 
removes any stray carbon dioxide ice from the tower 
reflux. Figures 13 and 14 show the column with heat 
exchanger equipment in the cold box. Further de¬ 
tails and an operating manual for the production 
model are available. 13 

Dri-Oxygen Compressor. A 2-throw-crank, 4- 
cylinder, water-cooled, vertical, single-acting, tandem- 
type Dri-Oxygen compressor serves the cylinder 
charging end of the system (see Chapter 6). The 
machine will continuously charge five standard oxy¬ 
gen cylinders per hour to a terminal pressure of 2,200 
psi. This machine utilizes Graphitar piston rings and 
consequently requires no water for lubrication. The 
compressor is driven through V belts by a Dodge 
clutch attached to the air compressor auxiliary drive 
shaft. 

Oxygen Analyzer. A special design oxygen ana¬ 
lyzer is provided. This is merely a modification of 
the standard ammonia type absorption analyzer 
unit. 14 

Instruments. Figure 13 shows the main instrument 
panel of the unit. The following types of instruments 
are supplied, all mounted on two large instrument 
panels facing the operating space in the trailer cab. 

1. Pressure gauges used are the Crosby Steam 
Gauge & Valve Company, Style AAO and AIH, 


4 1 /2-in. flush mounted, hack connection gauges and 
supplied for the following points. 


Service 

Range, psi 

First-stage discharge (air) 

0 to 

60 

Second-stage discharge (air) 

0 to 

160 

Expansion inlet 

0 to 

160 

Tower top 

0 to 

30 

Expansion engine brake 

0 to 

200 

Oxygen first-stage suction 

0 to 

15 

Oxygen first-stage discharge 

0 to 

100 

Oxygen second-stage discharge 

0 to 

300 

Oxygen third-stage discharge 

0 to 

800 

Oxygen fourth-stage discharge 

0 to. 

3,000 

2. Temperature gauges used 

are (1) 

Tagliabue 

vapor-pressure thermometers 12 ’ 11 

1 supplied for the 

following points: 



Service Temperature : 

range, F 

Cold high-pressure air 

+200 to - 

-315 

Expansion engine discharge 

+150 to - 

-325 

Cold low-pressure waste gas 

+200 to - 

-315 


and (2) Weston Electrical Instrument Company 
Model 221D, 3-in. dial, 6-in. stem thermometers used 
at the following points. (These items are not mounted 
on the instrument hoard.) 


Service 

Temperature range, F 

First-stage discharge (air) 

50 to 500 

Second-stage suction (air) 

0 to 200 

Second-stage discharge (air) 

50 to 500 

High-pressure air feed 

0 to 200 


3. A Meriam 16-in. Model A-275, panel-mounted, 
pot-type manometer is used for indicating liquid level 
in the low-pressure re-boiler. 

4. A Mason-Neilan Type 414, size 1-in., 0 to 37 psi 
range reducing valve is used to control the suction 
pressure to the oxygen compressor. 

5. A Bastian Blessing Company 8-cylinder, charg¬ 
ing manifold arranged so that four cylinders at a 
time may be charged, is supplied complete with the 
necessary pigtails for connection to the oxygen cylin¬ 
ders. The pigtails have Linde right-hand connec¬ 
tions, 0.903-in. diameter at the cylinder end. Oxygen 
cylinders are not supplied. 

6. Time cycle controller made by the Taylor In¬ 
strument Company (No. 177-RJ-223 Flex-O-Titner) 
for operation on 110-volt, 60-cycle current is used to 
operate the 4-way air reversing valve. 

7. A reversing valve, C. B. Hunt & Son, Model 
No. 9506-DP-4, 2-in. Quick-as-Wink double pilot 















24 


LOW-PRESSURE CYCLES AND UNITS 


operated, 4-way valve, actuated by the Taylor Flex- 
O-Timer is used to switch the air from one side of 
the reversing exchanger system to the other in the 
LP-1 cycle. This valve is located in the cold box. 

8. Miscellaneous instruments include the oil pres¬ 
sure and temperature gauges for the Clark Dri-Air 
compressor mounted on the instrument hoard, and 
the Weston Electrical Instrument Corporation ta¬ 
chometers for the expansion and Lycoming engines 
mounted on the instrument hoard. 

The oxygen compressor and the expansion engines 
are each equipped with oil level and pressure gauges 
mounted directly on each individual machine. 

3.2.3 Air Transportable Version of 
M-7 Unit 

The M-7AT unit was designed and built to answer 
a need for an oxygen unit which could he transported 
by airplane and set up for operation at an advanced 
base. 22 The M-7 cycle was the basis of the plant and 
it was constructed with a view toward extreme com¬ 
pactness and lightness in weight. The plant was con¬ 
structed in four sections, each of which was small 
enough to go through the doors of standard large 
military transport planes, and the weights of each 
section were within allowable air transportable limits. 
In the field the four sections can be connected rapidly 
by means of flexible hose and put into operation. 
Gasoline for fuel and power, and oil for lubrication 
were the only supply requirements aside from spare 
parts and tools. The units, completely boxed for ship¬ 
ping, had the following sizes and weights: 


Skid 

Dimensions 

(inches) 

Weight 
for shipping 
(pounds) 

Cold box 

36 x 38 x 90 

2,200 

Air compressor skid 

97 x 63 x 50 

2,950 

Oxygen compressor skid 

81 x 48 x 66 

1,950 

Expander skid 

27 x 50 x 65 

1,175 

Total weight 


8,875 


In addition to the above, there was required one 
box of spare parts and tools. Its size was approxi¬ 
mately 30 x 30 x 60 in. and the weight about 300 lb. 

The performance of the unit can he summarized 
as follows: 

Cooling down period, 14 to 16 hr; 

Flow of processed air, 12,000 scfh ; 

Operating pressure, 90 to 100 psi; 

Expander speed, 300 rpm. 


Production of the unit varies with purity and tem¬ 
perature of the surroundings. This can best he illus¬ 
trated in the following table : 


Inlet air 

Oxygen drawoff 

Temp F 

Dew point F 

Pressure psi 

scfh 

Purity % 0 2 

46 

45 

90.5 

674 

99.51 

103 

40 

92.4 

586 

99.57 

120 

80 

94.6 

536 

99.48 


Only one model of the M-7 AT was built. It oper¬ 
ated satisfactorily for a considerable period of time. 
It demonstrated the feasibility of constructing an ex¬ 
tremely lightweight high-capacity unit for high- 
purity gas production. Fuel consumption amounted 
to 0.16 gallon of gasoline per lb of oxygen produced. 
The unit had the minimum of control valves and 
gauges. It required very little skill to operate the unit 
successfully. A complete description and perform¬ 
ance data are covered in a series of reports. 16, 18 ’ 20 ’ 22 

Production Model 

When it had been demonstrated that the M-7 AT 
would operate successfully, a procurement order was 
placed with the manufacturers of the LP (M-7) units 
for an air transportable model of the LP units. 13 Ac¬ 
cordingly, a number were built using parts as nearly 
identical as possible to those previously described for 
the LP plant. Space rearrangements were made and 
there resulted a unit consisting of seven principle 
parts which could he conveniently connected and set 
up as shown in Figure 15. The general box construc¬ 
tion of the units makes use of aluminum Lindsay 
structure just as was done for the M-7AT unit. 

The following table gives weight data for each com¬ 
ponent part boxed for air transport. 


W eight 

Dimension for shipping 
Box (inches) (pounds) 


Engine 

39 i 3 

< 433 a 

<873 

1,680 

Air compressor 

394 ^ 

< 633 3 

<873 

2,500 

Oxygen compressor 

72 \ j 

c 553 3 

<523 

3,010 

Exchanger cold box 

863 3 

< 323 x 453 

2,560 

Tower cold box 

983 3 

< 343 3 

<393 

1,860 

Expansion engine 

663 : 

<273 3 

<523 

2,000 

Total 




15.110 


Each box was of such size that it could he handled 
and loaded on a C-47 transport plane. The unit will 





















LARGE-CAPACITY LIQUID OXYGEN PILOT PLANTS 


25 



Figure 15. Clark air-transportable oxygen generating unit, Model LPAS-3. 


produce 850 cfh of 99.5% oxygen with an ambient 
temperature of 80 F. 

3.2A Medium-Capacity Air Transportable 
Unit—the M-3 

At one time in the oxygen program it was thought 
that there might he a need for a unit to produce ap¬ 
proximately 350 cu ft of high purity oxygen per hour. 
To meet this requirement an M-3 unit (cold box only) 
was built using the cycle found to he successful in the 
M -7 operation. The unit was to be a small light¬ 
weight one which could be transported by plane and 
set up at an advanced air base. Apart from the de¬ 
sign of a smaller fractionating column than had been 
used on the AT unit, small Collins tubes were used 
and a new small reciprocating expander was devel¬ 
oped. The M-3 was built and, after some trouble, 
operated successfully. No service demand developed 


for this size unit and the program was not carried 
beyond the point of demonstrating successful opera¬ 
tion. 

Design and operating data are thoroughly covered 
in OSRD reports. 11 ’ 22 The compact nature of the 
equipment can best be illustrated by Figure 16 which 
shows the cold box under construction. 

3 3 LARGE-CAPACITY LIQUID 

OXYGEN PILOT PLANTS 

3 - 31 Low-Pressure M-5 Unit 

The Navy was interested in the development of a 
plant for the production of large quantities of liquid 
oxygen. A pilot plant, the M-5, was visualized and 
designed to produce 400 lb of liquid oxygen (95%) 
per hr from air at 100 psia, and to require no chemi- 






















26 


LOW-PRESSURE CYCLES AND UNITS 


cals for air clean-up or drying. 6 Other requirements 
were that the plant should he capable of operating on 
shipboard under the rocking conditions of a ship. 
It should operate for short continuous periods of 
8 to 10 hr, after which it would stand idle for 14 to 
16 hr; then operate again for another 8-hr period, 
and so on. These particular requirements for inter¬ 
mittent operation were later modified to make the 
operation continuous for a number of days at a time. 
The program on the M-5 was laid out with intermit¬ 
tent operation as the goal and the process design was 
made accordingly. A parallel development, the M-6, 
for the same goal hut based upon 600 psi air pressure 
is described in the next section. 


— 




Figure 16. Rear view of M-3 cold box showing check 
valve assembly, liquefier, and exchangers. 


When it was found that it would be more feasible 
to operate this large pilot plant on the M-7 cycle, the 
original M-5 process cycle was modified and the final 
M-5 plant is considerably different from that which 
was first visualized. 11 ’ 22 A maximum height require¬ 
ment was specified at 14 ft. This requirement also 
had a definite bearing on the process layout. A single 
column-type cycle was required rather than a double 
column in order to meet the specifications. 


The Kellogg M-5 Regenerator Plant 

A brief description of the original M-5 process 
follows. 

Figure 17 is a flow sheet showing operating data 
for the original M-5 plant. 6,11 Design was based 
upon air having a maximum dry-bulb temperature of 
100 F and saturated at 80 F. This air was cleaned 
of dust in a filter and compressed by a two-stage 
diesel-driven reciprocating air compressor to 100 
psia. An intercooler and aftercooler were designed to 
cool the air to 95 F, with sea water entered at 85 F 
and discharged at 100 F. 

Air from the aftercooler was passed through a 
centrifugal filter, a sintered metal filter and finally 
through a paper filter. These three filters removed 
all condensed water and oil particles from the air 
stream. Part of this cleaned air (about 75%) was 
used to supply the necessary refrigeration and the 
remainder was liquefied and fractionated. The clean 
air passed warm and switching valves and went to 
regenerators where it was cooled to —230 F. All 
water and carbon dioxide were frozen out in the re¬ 
generators. Four regenerators were used, arranged 
in two pairs. The high-pressure air was switched 
from one to the other of each pair at 3-min intervals. 
The switching of the two pairs was staggered. The 
reversing valves mentioned previously were con¬ 
trolled by an interval timer which utilized a pneu¬ 
matic device for activating the valves. Check valves 
were provided at the low temperature and the regen¬ 
erators. By this arrangement, air passed through two 
regenerators in parallel giving up heat to the packing 
which had been cooled previously by the effluent 
waste gas. Impurities in the air (CCL, FLO. hydro¬ 
carbons, etc.) were deposited in the regenerator pack¬ 
ing but were not completely removed by sublimation 
and evaporation by the returned gas in the reverse 
period of the cycle. 

The cold air leaving the regenerators passed 
through a bed of silica gel for the purpose of equaliz¬ 
ing variations in temperatures of the cold gas, to 
remove most of the hydrocarbons and solids not re¬ 
moved in the regenerators, and to provide additional 
volume to reduce pressure surges which occur when 
the regenerators were switched. During the start-up 
operation of the plant, the silica gel was used to 
remove the last traces of water from the air to pre¬ 
vent freezing in the passages leading to the expander. 

After the equalizer, the main air stream was di¬ 
vided so that about 25% passed to the liquefier and 
about 75% was sent to the turbo-expander. The 






























oODDD 



FLOW CU FT/MR 
ENGINE R P M 
PURITY % OXYGEN 
PRESSURE LBS /SO IN.GA 


Figure 17. M. W. Kellogg Co. pilot liquid oxygen unit M-5, 400 Ib/hr, mechanical low-pressure system, process flag sheet. 




























































































































































































































































































































































LARGE-CAPACITY LIQUID OXYGEN PILOT PLANTS 


27 


liquefier served as a partial condenser for the air to 
be processed. The air passing through the turbo¬ 
expander dropped in temperature from —230 F to 
—308 F. This temperature drop was accompanied 
by a pressure drop from about 90 to about 22 psia. 
1 he energy given to the expander during the expan¬ 
sion of the gas was absorbed through a set of gears 
by an electric generator. In the pilot plant the cur¬ 
rent from the generator was absorbed by a bank of 
resisters. A cloth filter was provided beyond the ex¬ 
pander outlet to filter out any solid carbon dioxide 
which might have been precipitated during the expan¬ 
sion. Part of the expanded air was introduced into 
the fractionating column very near the top and acted 
as a vapor feed. The remainder of the expanded air 
was sent to the liquefier and then, together with 
effluent from the tower, was sent to the regenerators. 

That part of the air stream which passed through 
the liquefier was sent to the tubular reboiler at the 
bottom of the fractionating tower where it was com¬ 
pletely liquefied. This condensation took place at 
about —284 F under a pressure of 80 psia. The con¬ 
densing of this air stream provided the heat to reboil 
the liquid in the bottom of the fractionating tower. 
The liquid air from the high-pressure side of the 
reboiler passed through a filter to remove any solid 
carbon dioxide particles, passed through a subcooler 
countercurrent to tower overhead and was cooled to 
—297 F. Having left the subcooler it passed through 
an expansion valve and provided the liquid reflux 
as well as rich feed for fractionation. Liquid oxygen 
on the low-pressure side of the reboiler was with¬ 
drawn as product. 

Waste gas, rich in nitrogen, was taken from the 
top of the tower through the subcooler and liquefier 
and back to the regenerators. Figure 18 shows the 
diesel and compressor for the M-5 unit and Figures 
19, 20, and 21 are pictures of the cold box. Operating 
characteristics of the M-5 regenerator plant are given 
in Table 3. 11 The operating record of the M-5 plant 
with the regenerators is shown in Table 2. 15,17 

There were two principal difficulties in the opera¬ 
tion of the M-5 unit in its original form with regen¬ 
erators. The Stedman fractionating tower proved to 
he inadequate and difficult to operate (see later chap¬ 
ter on fractionation). The poor tower performance 
resulted in low-purity oxygen although such produc¬ 
tion did not interfere with the rate of liquid produc¬ 
tion or result in serious changes of condition in other 
parts of the plant. It was found that regenerator 
plugging was quite rapid and thawing or shutdown 


was necessary at intervals of from 6 to 12 hr. Vari¬ 
ous thawing methods were tried, but none of them 
permitted uninterrupted operation of the plant for 
long periods of time. The plant, however, did meet 
original requirements regarding intermittent opera¬ 
tion but by the time the M-5 plant was operating, the 



Figure 18. Diesel engine and compressor—inter-coolers 

at right, M-5 unit. 

M-7 cycle had been proven satisfactory. It was there¬ 
fore felt desirable to incorporate the reversing heat 
exchanger principle in the M-5 plant and after the 
runs listed in Table 3, the plant was revamped to in¬ 
stall Collins heat exchangers. 22 One very notable 
achievement had been marked during these first runs 
of the M-5 plant, namely, the very successful opera¬ 
tion of the turbo-expander. This work is covered in 
detail in Chapter 5. Complete specifications, process 
calculations and experimental results for the M-5 
plant are found in other reports. 11-22 

The M-5 Heat Exchanger Plant 

The M-5 cycle was revised primarily to change 
from the use of regenerators to the reversing heat 
exchangers. In addition a tray column was designed 
especially for the unit (see Chapter 8) and a number 
of minor changes made as a result of previous oper¬ 
ating experience. For the most part, these later 
changes simplified the equipment and operation. The 









28 


LOW-PRESSURE CYCLES AND UNITS 



Figure 19. Uninsulated cold box—end view showing regenerators, M-5 unit. 


























LARGE-CAPACITY LIQUID OXYGEN PILOT PLANTS 


29 



Figure 20. Uninsulated cold box—end view showing tower and G-3 low-pressure filters, M-5 unit. 


four regenerators were replaced by two parallel banks 
of Collins type heat exchangers. Thirty exchanger 
tubes were used in each bank. Their location in the 
unit is shown in Figure 22. Figure 23 shows the 
M-5 plant ready for operation with the control hoard 
on the left and the turbo-expander installation at the 
right. The revised flow sheet is shown in Figure 24, 
together with operating data showing production-rate 
and operating characteristics. 

The M-5 plant with reversing heat exchangers 
differs in several particulars from the M-7 flow sheet 


of Figure 5. In the first place, the M-5 cycle is de¬ 
signed for liquid oxygen production, whereas the M-7 
cycle is designed for gaseous oxygen production. 
The M-5 requires much more refrigeration per lb 
of oxygen produced than does the M-7 plant, simply 
because one plant produces liquid, whereas the other 
produces gas. The other principal difference be¬ 
tween the two cycles is that the “unbalancing” stream 
in the M-7 cycle makes use of low-pressure nitrogen 
whereas the unbalancing stream in the M-5 plant 
makes use of high-pressure air. It has been shown 












30 


LOW-PRESSURE CYCLES AND UNITS 



Figure 21. General view of insulated cold box, M-5 unit. 


that carbon dioxide removal is completely achieved 
more easily hy the high-pressure air unbalance rather 
than low-pressure unbalance. 11 ’ 22 

The performance of the exchangers was in gen¬ 
eral much superior to that of the regenerators. It 
was possible to operate continuously for long periods 
of time (upwards of 10 days). Some further experi¬ 
mentation is still necessary, at this writing, to ar¬ 
range the heat exchanger system and the filtering 
mechanism between the aftercooler of the com¬ 
pressor and the cold hox to insure complete removal 
of entrained water from the compressor air. Per¬ 
formance data on the operation of the plant is cov¬ 
ered in detail elsewhere. 22 

A further development in the design of reversing 
exchangers has led to a much more compact and 
efficient reversing heat exchanger than the Collins 


design. This rectangular heat exchanger described 
in Chapter 7 is being constructed in a large size, 
suitable for installation in the M-5 unit. These heat 
exchangers are to be installed and, after other minor 
modifications, the plant will be ready for further 
tests. It is anticipated that continuous performance 
over long periods of time can be achieved by the new 
heat exchanger and process arrangements. 

3 3 2 Intermediate Pressure 

Air Reduction Company M-6 Unit 

Paralleling the low-pressure liquid oxygen pilot 
plant M-5, a medium-pressure cycle was devised and 
a plant constructed for the production of approxi¬ 
mately 400 lb per hr of liquid oxygen with a purity 
of at least 95%. The air pressure used in the plant 



























LARGE-CAPACITY LIQUID OXYGEN PILOT PLANTS 


31 



Figure 22. Cold box of M-5 unit showing reversing heat exchangers and air piping. 














































































32 


LOW-PRESSURE CYCLES AND UNITS 


Table 2. M-5 operating record. 


Run 

No. 

Starting 

date 

Actual 

operating 

hours 

Cause of shutdown 

Subsequent revisions 

1 

5/19/44 

28 

Compressor coupling failure 

Revised tower distributor; revised equal¬ 
izer flow. 

2 

6/ 5/44 

156 

Voluntary 

Revised tower distributor and turbine noz¬ 
zles ; installed equalizer dust filter and 
regenerator control dampers. 

3 

8/ 1/44 

14 

Turbine bearing failure 


4 

8/10/44 

44 

Liquefier and generator failure 


5 

9/12/44 

12 

Expander oil pump failure 


6 

9/19/44 

115 

Numerous 

Enlarged regenerator dampers; installed 
tower feed meter. 

7 

10/19/44 

160 

Voluntary 

Revised tower distributor, reflux filters, 
and turbine nozzles. 

8 

12/ 8/44 

110 

V oluntary 


9 

2/13/45 

10 

Voluntary 

Substituted reversing exchangers for re¬ 
generators and Type J tray tower for 
Stedman tower. Removed turbine ex¬ 
haust filters. 

10 

5/ 9/45 

170 

Exchanger plugging probably with CO 


11 

5/30/45 

2-10 

V oluntary 




Figure 23. M-5 unit—cold box installation and panel board. 













































LARGE-CAPACITY LIQUID OXYGEN PILOT PLANTS 


33 


Table 3A 


OPERATORS 


CatUrtll-fltSljna-flanMT.t 


-4 P. W i TO 


Cftff-Mohrtni^-Dnnn 



MLd. 


CENTRAL ENGINEERING LABORATORY 
UNIVERSITY OF PENNSYLVANIA 


H.D.R.C. SEC. II.I 


October 22 , 1944 

Sun l». 7 


PILOT PLANT OXYGEN UNIT M-5 
MECHANICAL LOW PRESSURE SYSTEM 

DATA SHEET 


SHEET BO. 1 

Eefer to Sheet No. 2 for 
Teaperetures, Flo* Retee, and Etc. 


TIME 


PRESSURES - P S I G 



COM¬ 

PRES¬ 

SOR 

FIRST 

AIR 

RETURN GAS - PP -5 

REFLUX 

LIQUIO 

-pp-e 

HIGH PRESSURE AIR- 

PP - 3 

EXP'R 

TURBINE OIL 

TOWER PACKING 

REGENERATORS 




. .. 


TOWER 

TOP 

SUB- 

COOLEF 

LIQUE - 

FIER 

REGEN¬ 

ERATOR 

CON- 

>ENSEF 

SUB- 

lOOLER 

OUT 

SPRAY 

EXP'R 

IN 

LIQUE- 

FIER 

EQUAL 

IZER 

EQUAL¬ 

IZER 

OUT 

BEAR¬ 

ING 

GEAR 

FEED 

TRAP 

TURBINE 

FEEO 

TOTAL 

A-C 

B-C 

0-B 

0-A 

FUJEF 









OUT 




OUT 

IN 

OUT 


FEEO 














PP.| 

PP-2 

PP-5-1 

PP-S-2 

PP- 5-3 

PR- 5-4 

PP-6-1 

PP-B-2 

PR6-3 

PR-J-I 

PRJ-2 

PR 3-3 

P P-3-4 

PP-4 

pp-7 

pP-9 

pP-0 

XZ 

YZ 








REMARKS 

. 

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6 mZ 

6.1 

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9.4 

72 

67 

55 

72 

75 

70 

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6.6 

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8.0 

2.7 


9.5 

9.4 

9.5 

9.4 

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4“ 

44 

7fl 

8.6 

6.1 

5.1 

0.4 

72 

68 

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72 

78 

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70 

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44 

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80 

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5.8 

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82 

86 

87 


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ftft 

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82 

7.0 

ft. 7 

6.7 

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79 

75 

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Aft 

ftft 

7 ft 

An 

ft 

19 



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7.ft 


77 

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4.6 

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10 

9 

9 

78 

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ft. 9 

an 

A 

17 



1.7 








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45 

78 

7.8 

7.5 

6.4 

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72 

64 

50 

68 

71 

78 

74 

8.2 

an 

a 


7.a 

2.. ft 

5.4 

15-0 

1-2-7 

19.7 


1 A 



5 15 


75 

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7.R 

7.0 


67 

6? 

4ft 

A4 

67 

67 

6 ft 

A 9 

80 

8 

17 



5-4 

12.5 

ll.fi 

12.6 

15.8 




45 
ft - 

45 

78 

8.0 

7.8 

6.9 

0.4 

76 

67 

4ft 

75 

76 

8? 

80 

ft. 4 

an 

ft 

17 



1.8 

11.5 

11-Q 

12,7 

14.9 




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4 — 

45 

78 

8.5 

6.0 

Or 9 

0.5 

72 

67 

47 

71 

66 

71 

66 

8,2 


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14.5 


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PRESSURE DROPS - IN. HG. 


Table 3B 


OPERATORS 

_LLM T 0 12 M id. 


CENTRAL ENGINEERING LABORATORY 
UNIVERSITY OF PENNSYLVANIA 

N O.RC. SEC. II.I 



LIQUID 


TURBO-EXPANDER 


FLOW RATES 


TEMPERATURES 


LEVELS 


PROOUCT - FI-7 


LOAD 


LOAD 

VOLT. 

AGE 


REGENERATOR SWINGS 


VAPOR 


■RETURN 

GAS 

OUT 


OIL 

TO 

TUR¬ 

BINE 


AIR 

FEED 


RETURN GAS 


EQUAL 

IZER 

OUT 


LIQUID 
■ FEED 


EQUAL 

IZER 


EXP' R REB'R 
OUT LIQUID 


CON 

>CNSER|C0OL£EffoWER 
.(QUID *FUIX TOP 


TEMP 


FLOW 

LB/Mfl 


CUR¬ 

RENT 

AMP 


FEED 


FEEO 


iTATIC 
PRESS 
IN MG 


DIFF 
PRESS 
IN M-,0 


TO 

COOLER 


LIQUE 

TIER 

OUT 


JQUE 

FIER 

IN 


SC F M 
XIO* 4 
FI- 4 


SCFH 
X 125 
FI - S 


SCFH 
X 10*' 


October 22, 1044 
Run No. 7 


PILOT PLANT OXYGEN UNIT M-5 
MECHANICAL LOW PRESSURE SYSTEM 
DATA SHEET 


t ru— .... _ 

beet No. 1 ror 
Pressures, pressure drops, 


etc. 


. A.M. 


Goff-Mahoney-Dunn- 12.JL1A. 























































































































































































































































34 


LOW-PRESSURE CYCLES AND UNITS 


Table 4 


OPERATOR 

LOAD, HAAP1TEI, RIFF 

HUT 



TO_ 

* Pjyl 

If P.M 

• AW 







PILOT LIQUID OXYGEN UNIT M-6 
MECHANICAL MEDIUM PRESSURE SYSTEM 
DATA SHEET 









RUN N 
I2 

CATE 

10 

6 


SHET 

NQ_ 

6 A .M 

XIRL 

1 


AEA0 03, 

A 0T LI 

um 


P.M 

_HOURS END INK 

MIT II 

LAMf, 3IRAEA, 

•09TTC 

_If 

AM 

,id4 


PM. 

PRESSURES, PS I G. 

TEMPERATURES *F 

FLOW RA 

LBS PER 

rES 

PRODUCT 

IQ LEVEL 

H.L.E 

UPLOAD 

H P. AIR 

MEDIUM PRESSURE AIR 

RETURN GAS 

H P AIR 

EXPANDERS 

MED PRESSURE AIR 

RETURN GAS 

HR 



*PM 

BRAKE 


RRl 

MAIN 

.omr 

HLCXP 

-LEXP 


SOB- 

IM7-* 

rcTtn 

«c 


sue- 

-Ollf 

MA.N 


p«. 

PRC 

<Xtr 

wkx level 


_£YEL 

5UPCR 

JOUIO 

COMO 

SJ8 


TOWER 


OXF 

iOI' 

PRC- 


A.A 


«TL*»N 

PROM 

TO 

| 


SCRUB 

1C- 


ORCE 

*<p 

TIME 

CCOUJ 

CAOi 

OUT 

OUT 

INUT 





nun 

TOR 

CCXXfP 

OUT 

ttOi 

coax* 

:ca_m 








ruo 


COOLER 

sou* 



NUT 

DUTUT 

xoxr 


nco 

rtco 

CAS 

TIME 

time 



OCR 

lOiun 


LBS 



IN 

OUT 





31/TUT 





VTUT 


DUTUT 

DUTUT 

INLET 

3UTUT 


•N 

OUT 

• N 


OUTLET 



Pmxa 



VTUT 



IMTT 


TO 

25 

50 



HOUR 1 

%o, 

12 





ADO 4 HR* 

PI.*- 


PP-O 

PP-5-1 

PP-VA 

PR-59 

PR-5-* 

PR-5 T 

RRBlO 

>R-*-| 

PR-9? 

PR-9 3 

PR* ■* 

PR-9-5 

•R-9-4 

TNI-3 



















R.-4 

ri-9 





XC-I 'L 

Ll-I 

l-» 



ItiM 

699 

696 

596 

61 

66 

59 

62 


52 

... 


3.1 

l.l 

l.l 

0.1 

•2 

39 

• 229 

• 61 

-211 

-246 

-287 

-294 


-201 

-219 

-267 

• 112 

•291 

•219 

-140 

II 

76 

il 

40 

•1 

136 

407 

429 

99.4 

0.1 

10 

280 

•2 

29 

if:* 

8 "0 

596 

697 

63 

M 

67 

51 


62 

6.9 

4.1 

S.8 

2.1 

l.l 

0.1 

81 

41 

-225 

-71 

-210 

-211 

-292 

■2ti 


-288 

• 299 

•299 

•112 

-211 

-tn 

-112 

26 

75 

61 

39 

II 

407 

441 

411 

99.60 

0.7 

10 

2ft0 

62 

29 

l:ll 

699 

590 

690 

•2 

67 

M 

61 


99 

5.9 

4.1 

l.l 

2.0 

l.l 

0.1 

II 

40 

-225 

-77 

-214 

-2**1 

■ 295 

-214 


-;ne 

•299 

-296 

-112 

• 292 

-29* 

• 111 

24 

75 

51 

40 

•9 

441 

519 

369 

99.59 

0.8 

10 

290 

62 

29 

l:ftft 

600 

596 

699 

62 

17 

M 

61 


60 

6.1 

4.1 

l.l 

2.0 

l.l 

0.3 

•1 

40 

-227 

-60 

-219 

-244 

-284 

-284 


-289 

-2M 

-287 

-112 

-293 

•211 

•140 

21 

75 

61 

41 

19 

611 

661 

410 

99.47 

0.7 

II 

280 

62 

29 

1:11 

600 

699 

699 

62 

67 

64 

61 


61 

6.1 

4.2 

l.l 

2.2 

1.2 

0.1 

•1 

40 

-228 

-63 

-2J5 

-248 

•2M 

-2M 


- 2 99 

- 2 88 

-267 

-111 

•293 

-289 

-141 

21 

71 

51 

39 

II 

563 

425 

444 

99.66 

l.l 

II 

280 

41 

29 

li» 

too 

696 

597 

62 

57 

64 

61 


98 

6.1 

4.1 

l.l 

2.1 

1.2 

OJ 

II 

40 

•221 

-94 

•240 

-249 

-267 

-261 


•211 

-299 

-297 

-111 

•291 

•219 

• 141 

21 

71 

(1 

42 

19 

626 

466 

459 

99.66 

0.9 

10 

280 

• 1 

29 

III! 

too 

699 

699 

62 

67 

66 

61 


96 

5.1 

4.2 

1.7 

2.1 

l.l 

0.1 

•1 

40 

•227 

-15 

-240 

-249 

-290 

•261 


•200 

-299 

-267 

-111 

-294 

•211 

-142 

21 

71 

61 

42 

•9 

664 

710 

422 

99.68 

1.0 

II 

290 

62 

29 

ft* 

too 

696 

597 

•2 

68 

64 

61 


94 

6.1 

4.1 

l.l 

2.1 

l.l 

0.1 

12 

40 

•229 

-15 

-240 

-249 

-290 

•291 


-211 

-281 

-267 

-112 

•293 

-299 

•142 

21 

71 

50 

40 

99 

730 

801 

460 

99.45 

..4 

10 

279 

«l 

28 

9:1ft 

600 

699 

699 

62 

67 

16 

50 


99 

6.1 

4.1 

l.l 

2.3 

1.2 

0.1 

II 

40 

-221 

• 96 

-241 

-249 

-290 

-291 


•211 

-2M 

-267 

-312 

-293 

-299 

-142 

21 

71 

61 

41 

69 

601 

•10 

411 

99.17 

1.6 

II 

276 

•2 

29 

• i* 

602 

900 

696 

61 

66 

66 

62 


49 

6.1 

4.2 

1.7 

2.1 

l.l 

0.1 

• 1 

40 

-229 

•96 

-241 

-260 

-299 

-284 


-210 

•299 

-207 

-112 

-291 

-217 

-142 

21 

7ft 

60 

19 

89 

630 

901 

461 

99.17 

1.0 

10 

290 

42 

29 

1:11 

606 

601 

600 

•2 

67 

56 

63 


44 

6.1 

4.1 

1.7 

2.1 

l.l 

0.3 

12 

40 

-227 

• 66 

-241 

-249 

-292 

•m 


•281 

•289 

-217 

-112 

-293 

-2U 

-142 

21 

7ft 

60 

17 

99 

901 

912 

466 

99.12 

0.9 

II 

290 

• 1 

29 

• :« 

601 

699 

698 

61 

67 

64 

61 


49 

6.4 

4.1 

l.l 

2.1 

l.l 

0.1 

• 1 

40 

-226 

-66 

-240 

-249 

-292 

•294 


•299 

-299 

-207 

-112 

-291 

-266 

-140 

21 

74 

61 

17 

90 

932 

1002 

470 

99.45 

0.6 

II 

275 

•2 

26 

•:1ft 

606 

600 

699 

61 

67 

57 

51 


46 

6.9 

4.1 

1.9 

2.1 

l.l 

0.1 

•1 

39 

-228 

•65 

-240 

-249 

-291 

■292 


•299 

-281 

297 

-y* 

-291 

-297 

-140 

21 

71 

61 

21 

69 

1002 

1030 

470 

99.16 

l.l 

10 

28 0 

•2 

29 

•:« 

606 

600 

600 

61 

66 

67 

69 


47 

6.1 

4.1 

1.8 

2.1 

l.l 

0.1 

II 

39 

-229 

•66 

-240 

•249 

-292 

■281 


-299 

-291 

■267 

-112 

-291 

-217 

-140 

21 

74 

61 

37 

99 

1030 

1101 

460 

99.34 

1.0 

II 

290 

•2 

29 

7: II 

601 

600 

699 

61 

67 

64 

61 


41 

6.1 

4.2 

l.l 

2.1 

l.l 

0.1 

62 

39 

-227 

-86 

-242 

-250 

-292 

-294 


•211 

-209 

-297 

-112 

-291 

• 219 

-141 

22 

74 

51 

17 

69 

1101 

11)0 

466 

99.16 

2.1 

10 

290 

•2 

21 

7:* 

606 

600 

699 

61 

56 

69 

61 


61 

6.1 

4.3 

l.l 

2.1 

1.2 

0.1 

« 

40 

-230 

-66 

-242 

-260 

-292 

•294 


-219 

-294 

■291 

-112 

-291 

•211 

-111 

22 

74 

51 

17 

•9 

1130 

1200 

472 

99.33 

1.6 

II 

290 

•1 

29 

•:1ft 

• 10 

606 

900 

• 1 

64 

56 

61 


62 

6.1 

4.2 

1.7 

2.0 

1.2 

0.4 

62 

40 

•229 

-17 

•241 

-261 

-282 

-214 


-299 

-217 

-287 

•112 

-294 

-297 

-144 

22 

74 

51 

31 

69 

1200 

1229 

.» 

99.4 

2.0 

10 

290 

•2 

29 

* ft:%ft 

606 

696 

696 

• 1 

64 

66 

61 


41 

5.1 

4.1 

l.l 

2.1 

1.2 

0.4 

62 

39 

•226 

• 66 

•241 

-260 

-291 

-2» 


•211 

-284 

-295 

-Ilf 

-211 

-217 

-141 

22 

74 

61 

16 

69 

1229 

1269 

466 

99.1 

2.0 

II 

290 

• 1 

29 

•:i» 

606 

600 

600 

62 

67 

66 

69 


41 

6.1 

4.1 

3.9 

2.2 

1 J 

0.4 

91 

19 

-229 

• 16 

-241 

-250 

-291 

-211 


-291 

-211 

-289 

-112 

-294 

-291 

• 141 

22 

75 

SI 

11 

70 

1269 

112 

424 

99.6 

2.6 

II 

290 

62 

29 

9iH 

• 10 

600 

600 

62 

67 

64 

61 


69 

5.4 

4.4 

l.l 

2.2 

1.2 

0.4 

91 

40 

•226 

-66 

-241 

-260 

-292 

•294 


-299 

-299 

296 

•112 

-292 

•299 

-141 

22 

75 ' 

61 

14 

99 

132 

201 

464 

99.6 

2.0 

II 

290 

•2 

29 

■•:(• 

606 

600 

600 

•2 

67 

66 

61 


61 

6.4 

4.4 

l.l 

2.2 

1.2 

0.4 

61 

40 

-227 

•66 

-241 

-260 

-292 

■294 


-216 

•218 

■299 

-112 

-292 

-299 

-141 

22 

7ft 

M 

31 

70 

203 

212 

466 

99.6 

3.0 

10 

290 

•2 

29 

10: Aft 

• 10 

600 

600 

•2 

59 

57 

99 


48 

5.4 

4.4 

l.l 

2.2 

1.2 

0.4 

•3 

40 

-227 

-66 

-*4f 

•250 

-293 

■ 284 


-291 

-280 

■299 

-112 

-293 

-299 

• 141 

22 

75 

62 

17 

70 

212 

104 

440 

99.3 

1.0 

10 

290 

• 1 

29 

lltil 

• 16 

606 

606 

61 

69 

69 

66 


59 

6.6 

4.4 

l.l 

2.2 

1.2 

0.4 

84 

40 

-228 

-66 

-241 

•260 

-291 

■293 


•219 

-2M 

-299 

-112 

-294 

• 261 

-Ml 

22 

71 

62 

17 

70 

304 

311 

460 

99.4 

2.6 

10 

290 

92 

29 

ll:M 

• 10 

•06 

606 

« 

67 

64 

61 


49 

6.7 

4.4 

l.l 

2 .2 

1.2 

0.4 

81 

40 

-227 

-15 

-242 

-250 

-292 

294 


-281 

-299 

297 

•112 

-291 

-2AA 

-141 

22 

75 

61 

31 

70 




99.1 

2.0 

14 

290 

•2 

29 

*«0UM 

60} 

600 

600 

62 

67 

64 




6.S 

4.3 







-277 

• 94 

-240 

-248 

-290 













31 

99 



449 

99.5 



280 


29 

IfMftD T k|s SHEET IS FI HAL 12 H0W1 

34 H0UA RUA - SHUT 00** AT 1:96 AM DUE TO LOOSE CAM OR MICH LEVEL EIR9R0EA 




























TOTAL liouio 

F900UCE0 F0A 12 HOUR REA 100 5362 LIS • 999 L9S/H0W 

99.6102 

HASTE IAS ANALYSIS AVfUIC 

'»•'» ®2 


























ietwr «as not calcuuteo from hate* manometer 

IEA0IH 

ON FI-5 ORIFICE 

RLATE 

4.011 

0 iam) 10.21* NjO AVEAAIC • 

•440 IDS/NOW 
























TOTAL 

IA FEED (AETUAR 8A3 FLW RAODOCTIOR) - *089 LBS/HOW - 910 CFM AT 19.70 ♦ 70°F, 0IT9ER 

II -.21 > 910 CFM 

• 19 

cfm, arm 

OUT - 

•0 « no - III CFM 



















fitM ME TEA FI-6, AETWH «AS - 

,(( ■ 

6000 - 

1960, 

A IA FEED - 

1460 * 

449 - 

1999 IIS /NOW - 116 CFM 

. 0IT8ER II 

- .2 

■ 146 

• It2 CFM, 

3IVCCI 

OUT • 

90 * 

III ■ 

776 - 

171 CFM 


















l.l. EIRAR0ER EFF. 

FROM AVIAA0E DATA 96ft. 

l.l 

EtRAROEA IFF. Hft, VAF08 FEED 1000 ll/AOUA • 

25ft OF All 

FEED 




























was 600 psia. I he low-pressure M-5 plant of maxi¬ 
mum compactness was ultimately dependent for suc¬ 
cessful operation upon the development of an effi¬ 
cient high-speed rotary air compressor and on the 
successful development of an efficient turbo-expander. 
Further, it was necessary to develop mechanical 
means for elimination of carbon dioxide, water, etc., 
from the low-pressure air stream. At the beginning 
of the program equipment was not available for 
achieving such a plant, although there was considera¬ 
ble promise of success. In contrast to the low-pressure 
M-5 cycle, a medium-pressure process operating at 
about 600 psia could make use of reciprocating com¬ 
pressors of standard design or lightweight compres¬ 
sors which might be developed for this particular 
pressure. Reciprocating expanders were already 
available to supply refrigeration for such a unit al¬ 
though it was felt desirable to improve the design of 
commercial expanders available at that time. For 
earbon dioxide and water removal, switching heat 
exchangers and cloth filters were thought to offer 
excellent possibilities for success. Owing to the 


higher pressure of operation, many of the heat ex¬ 
changer elements and piping could be reduced in size 
more than that required for the lower pressure unit. 
It was felt that carbon dioxide and water could be 
removed successfully by mechanical separation, fil¬ 
tration, and switching. The two cycles, M-5 and M-6, 
thus represented two distinctly different processes 
whereby air could be compressed, cleaned and used 
for all necessary refrigeration. The two processes 
were developed at the same time with the hope that 
at least one of them would prove successful in all 
respects. The lower pressure cycle seemed to offer 
greater possibilities for simplified lightweight very 
large capacity plants with high efficiency, whereas 
the M-6 cycle offered the best possibility for quick¬ 
est realization of the immediate Navy requirement 
for large liquid oxygen plants. 

The general specifications for the M-5 and M-6 
pilot plant follow. 

Production over 400 lb per hr of liquid oxygen 
at 95/f purity or better; power consumption to be 
0.5 brake horsepower per lb of liquid oxygen. 
























































































































































oODOO 


BUTTERFLY 



PURITY % OXYGEN 
PRESSURE LBS/SQ IN. GA 

Figure 24. M. W. Kellogg Co. pilot liquid oxygen unit M-5, 400 lb/hr, mechanical low-pressure system, process flagshcet. 








































































































































































































































































































































































































































































































































































LEGEND 



Fic.uke25. M. W. Kellogg Co. pilot liquid oxygen unit M-6, process flagshcct. 



















































































































































































































































































































34 


- 


~ 










































pre: 


pre; 



ava 
the, 
con 





































Figure 26. Front view M-6 unit. 


The plant to operate under rocking conditions of 
6 cycles per min at 15 degrees from the vertical in 
any direction. 

Total space to he occupied by the plant, including 
air compressor, to be 15x17x15 ft high. This 
severe space limitation practically ruled out the use 
of chemicals and water and carbon dioxide removal 
and in any event it was highly desirable to develop a 


plant which would not require chemical supplies for 
such purposes. 23 ’ 24 

The designed process flow sheet for the M-6 plant 
is shown in Figure 25. 

The process was designed to operate as follows: 

Air at 100 F saturated at 80 F is drawn through a 
dust filter to a three-stage diesel-driven reciprocating 
compressor and discharged at 600 psia. 








36 


LOW-PRESSURE CYCLES AND UNITS 



Figure 27. M-6 pilot plant—general view—expanders and cold box. 


Two interstage coolers and an aftereooler reduce 
the temperature of the air to 95 F with sea water at 
a maximum of 85 F at the inlet and 100 F at the out¬ 
let. Air from the aftercooler is passed to a drum in 
which condensate is cooled and removed. The air 
then passes to an oil filter where paper or glass and 
oil particles are separated from the air. 

All refrigeration required in the process is ob¬ 
tained by the use of expansion engines operating at 
two different pressure levels. Thus, part of the air 
entering the system is used for refrigeration and the 
remainder is liquefied and separated to obtain the 
liquid oxygen product. 

The dirt-free, high-pressure air is cooled to about 
40 F in a precooler, located outside the cold box, 
where the bulk of the water vapor is condensed and 
removed as liquid through a centrifugal separator. 
The air then passes to one of two heat exchangers 
placed in parallel so that while one is in use the other 
can he thawing. Air is cooled in these exchangers 


to about —130 F and any water vapor which remains 
after the precooler is frozen out and allowed to ac¬ 
cumulate in the shell of the exchanger. After a suita¬ 
ble period of time, and before the exchanger is fouled 
badly by accumulated ice, the parallel exchanger is 
switched into the stream and a blast of warm dry 
effluent gas from the process is allowed to pass 
through the exchanger with accumulated ice. This 
process is repeated cycle-wise throughout the opera¬ 
tion. The cold air from these exchangers is passed 
to a liquefier where it is cooled below the critical 
temperature, and a portion of it is liquefied. This 
mixture of cold and liquid air then proceeds to the 
high-pressure side of the reboiler where it is com¬ 
pletely liquified and gives up heat to the boiling oxy¬ 
gen in the column. The liquid air then passes through 
a subcooler, a filter, and a reducing valve from which 
it passes directly to the top of the tower supplying 
feed and reflux. The other portion of the air from 
the main exchanger is taken to a high-level expansion 




















LARGE-CAPACITY LIQUID OXYGEN PILOT PLANTS 


37 



Figure 28. M-6 pilot plant—operating space—instrument panel and controls. 


engine where pressure is allowed to drop to 74 psia. 
The corresponding temperature drop is from —130 F 
to —250 F. Solid carbon dioxide is precipitated 
during this temperature change and a cloth type filter 
is used to block the flow of the solid carbon dioxide. 
The filters are a parallel pair and can be used alter¬ 
nately so that from time to time they can be blown 
free of solids. Part of the filtered 74 psia air stream 
is taken to a set of four low-level expansion engines, 
where the air is expanded to about 16 psia and its 
temperature is reduced to about —285 F. The 600 
psi filtered air from the liquefier is expanded to 74 
psia and is then mixed with the remainder of the 
74 psia stream and subsequently filtered in cloth-type 
filters. 

The air exhaust from the low-level expanders is 


led into the fractionating column near the top and 
acts as a vapor feed. A small amount of oxygen is 
recovered from this stream. Liquid oxygen is with¬ 
drawn from the bottom of the column, and vapors, 
rich in nitrogen, are taken from the top of the column 
and their refrigeration recovered by passing through 
the subcooler, the liquefier, and the main exchanger 
to the precooler. The equipment was designed to 
allow discharge of the effluent gas at 7 F below the 
temperature of the high-pressure feed. 

Details of individual pieces of equipment and their 
operating characteristics are given in later chapters; 
for complete reference see OSRD reports. 11 * 22 Fig¬ 
ures 26, 27, 28 are views of the pilot plant. Table 4 
is a typical operating data sheet for the M-6 plant. 

Plant operation was achieved for extended periods 


























38 


LOW-PRESSURE CYCLES AND UNITS 


of time and after proper operating technique was 
developed, it was found that carbon dioxide and 
water could be removed by the switching exchangers 
and filters. It should be remembered that original 
specifications for these large liquid oxygen plants 
require them to operate for short periods of time only. 
The M-6 plant has been demonstrated to be capable 
of operating for production periods of 8 to 10 hr, 
followed by 10- to 20-hr periods of shutdown. In 
this intermittent type of operation no difficulty is 
experienced with water or carbon dioxide blocking 
and the unit achieved its original goal. The test runs 


showed, however, that it was also possible to operate 
for longer continuous periods. This now seems to 
be the desirable method of operation, and the unit is 
satisfactory for such purposes. The best performance 
for an extended period of time gave the following 
results: 

For a continuous 72-hr period with head pressure 
600 psi and air flow 4,100 lb per hr, there were pro¬ 
duced 418 lb per hr of liquid at net horsepower re¬ 
quirement of 323, corresponding to 0.77 lip per hr 
per lb of liquid oxygen; the oxygen purity was 
99.5% and oxygen recovery was 44%. 24 




Chapter 4 

HIGH-PRESSURE CYCLES AND UNITS 

By J. H. Rushton 


INTRODUCTION 

or CERTAIN requirements of the services it 
seemed advisable to develop oxygen production 
plants based upon high-pressure cycles. Six separate 
projects were carried through to completion, based 
on high-pressure air for production of both gaseous 
and liquid oxygen. Two of these units were devel¬ 
oped primarily for use aboard a submarine, where 
extreme compactness in size was desired, and where 
the unit was designed to produce liquid oxygen for 
storage for breathing purposes aboard the submarine. 
The other four units were built for mounting on a 
trailer or on shipboard, using torpedo-charging com¬ 
pressors to supply this high-pressure air. In addi¬ 
tion it should he noted that a so-called intermediate 
pressure (600 psi) plant (M-6) is described in Chap¬ 
ter 3. 

4 2 KEYES UNIT 

A direct expansion refrigeration plant of very com¬ 
pact design has been perfected, and several models 
built, leading to a design suitable for mass produc¬ 
tion. 1,3 ’ 4 ’ 10 The original desire for a compact plant 
to produce liquid oxygen for replenishing the gaseous 
oxygen of a submarine atmosphere resulted in the 
first of the Keyes units. The unit was to be supplied 
with air from compressors normally used to charge 
high pressure air into the submarine torpedo charg¬ 
ing flasks. These submarine torpedo charging com¬ 
pressors had a normal capacity of 300 lb per hr of 
air discharged at 3,000 psi. The unit was to he of 
such dimensions as to pass through the conning tower 
hatch of a submarine. With the available air supply, 
the unit was designed to produce from 15 to 18 lb per 
hr of 98-)-% liquid oxygen when operated without 
any precooler refrigeration. With the aid of a Freon 
refrigeration machine to effect forecooling, produc¬ 
tion was anticipated at between 35 to 40 lb per hr. 
A prototype was built and operated successfully; a 
flow sheet for it is given in Figure l. 2 The cycle is a 
simple high-pressure Joule-Thomson one with water 
and carbon dioxide removed by alumina and solid 
caustic soda. The alumina is contained in cylinders 
and can be re-activated; the caustic is in pellet form 


in cylinders and can he replaced from time to time. 
Warm, dry, CCX-free, high-pressure air is led to the 
unit where it enters heat exchangers which may or 
may not he attached to a Freon forecooling machine. 
The clean high-pressure air is cooled by counter- 
current heat exchange with nitrogen effluent and 
passes through the condenser side of the reboiler. It 
then passes through an activated carbon filter for 
the removal of the last traces of carbon dioxide after 
which it passes through an expansion valve where 
the pressure is released from 200 atmospheres to 
approximately 1 atmosphere. Feed and reflux are 
supplied from this stream and boiling liquid oxygen 
is removed from the reboiler as production. Effluent 
nitrogen from the top of the column is returned 
through the heat exchangers and is used for re-acti¬ 
vation of the alumina. 

Four manufacturing models of the Keyes unit were 
made and equipped for use with or without Freon 
forecooling. 4 Two of these models were sent to Great 
Britain for tests and two were retained for use in 
NDRC and Navy laboratories. The cold box was 
constructed within an aluminum cylinder 18 in. in 
diameter and 15 in. in height. This contained all the 
heat exchanger and rectifying equipment. The total 
weight of this part of the unit was 175 lb. The oil- 
water separator, caustic soda tube, and aluminum 
drying tubes were contained in cylinders 48 in. long 
and of various diameters up to 6 in. The total weight 
of this cleanup equipment was about 450 lb. It was 
mounted on a single frame adjacent to the cold box. 
An air-cooled Freon refrigeration unit, weighing 470 
lb complete with motor, occupied a space of 39 x 
31 _)/2x25 in. high. A flexible delivery tube was 
provided for conveying the liquid oxygen produc¬ 
tion from the unit to suitable storage flasks. An¬ 
other feature of this high-pressure plant is its short 
start-up time. Liquid oxygen can be drawn off the 
unit within 45 to 60 min after operations are started. 
These are the conditions when the unit is completely 
warm. After the unit is cool, a shorter time of start¬ 
up can be obtained. Figures 2, 3, and 4 are pictures 
of the Keyes unit. These units have operated very 
successfully and have proved to he rugged and thor- 



39 


40 


HIGH-PRESSURE CYCLES AND UNITS 



Figure 1. Keyes submarine air conditioning liquid oxygen unit. 


oughly dependable. Several of the automatic fea¬ 
tures, particularly the liquid level control and the 
automatic expansion valve, have proved to be most 
satisfactory. One of these units has been in almost 
daily use for several years supplying liquid oxygen 
for experimental purposes in the Central Engineer¬ 
ing Laboratory of this Section. It operates without 
difficulty and requires the minimum of attention and 
maintenance. 

By the time the four models just mentioned were 
produced, there was under development an air-acti¬ 
vated liquid oxygen pump (see Chapter 6). Further¬ 
more, it was felt desirable to extend the usefulness 
of the Keyes unit from a liquid producer to a gaseous 
oxygen producer. The liquid pump, applied to the 
Keyes unit, would enable it to produce gaseous oxy¬ 
gen at high pressure, if so desired. With these ad¬ 
vantages in mind, a modified Keyes unit was laid 
out and a prototype liquid pump unit was built, in¬ 
corporating the liquid pump in the Keyes unit. This 


pump model was successful in operation and a design 
was laid out for production models of the Keyes unit 
with liquid pump. It was also desirable to produce 
higher purity oxygen (99.5%) for engineering and 
aircraft breathing purposes. It was decided to incor¬ 
porate a rotating column in the unit to allow opera¬ 
tion under rolling conditions as encountered on sur¬ 
face ships of the Navy, and to step up the capacity 
of the unit so that 540 lb per hr of air at 3,000 psi 
(120 cfm) could be used. On this basis, oxygen pro¬ 
duction should he at least 70 lb per hr. Forecooling 
by Freon was provided when liquid oxygen was to 
be the product, hut was not required for the produc¬ 
tion of gaseous oxygen at 2,000 psi. Further, for 
production of high-pressure gas, the air feed pressure 
could be reduced. A flow sheet of the pump unit is 
given in Figure 5. Two such pump units are now in 
the course of construction. They will be rectangular 
and will occupy a space approximately 3x5x7 ft 
high, without air compressor. 3 ’ 10 



















































































KEYES UNIT 


41 



Figure 2. Keyes S-1,000 unit (335 lb) connected to Freon forecooler (1,000 lb) and showing cleanup system 
(900 lb) in center background. Liquid 0 2 , 35 lb per hr, 98+ per cent purity. 


























42 


HIGH-PRESSURE CYCLES AND UNITS 



Figure 3. Keyes unit, Servel model. Top plate assembly. 


H.P. 

High pressure air connection 


N.E. 

“Nitrogen” effluent outlet 


O.D. 

Oxygen product (liquefied) delivery 

Liquid level attachment joints: 


L.L. 

Liquid at bottom of rectifier 


L.G. 

Wall of rectifier above liquefied 0 2 level (gas 
equilibrium with liquid 0 2 ) 

in 

O.V. 

Hand operated liquefied oxygen delivery valve, 
passing float valve 

by 

R.V. 

Relief valve on high pressure line between filter 
for solid C0 2 and expansion valve 

R.D. 

Rectifier relief diaphragm 


G.X. 

Pressure gauge before expansion valve 


G.R. 

Pressure gauge to rectifier (0 — 50 psi) 


XV. 

Expansion valve cover 


F.L. 

Liquid Freon-12 line 


F.G. 

Gaseous Freon-12 line 


F.D. 

Oil drain on Freon interchanger 




Figure 4. Keyes unit, Servel model. 

A. H.P. O, 0—3,000 pressure ga. 

B. Rectifier 0—50 pressure ga. 

C. H.P. Exp. Valve 0—4,000 pressure ga. 

D. Air Inlet 0—4,000 pressure ga. 

E. Liq. Level Ga. 0—5 in. of H 2 0 

F. 0 2 Manifold 0—3,000 pressure ga. 

G. Air exch. pump valve 

H. Air inlet pump valve 

I. Boiler drain valve 

J. Gas valve 

K. Liquid valve 

L. Oil drain 


43 ARTHUR D. LITTLE-LATHAM 

UNIT 

A second high-pressure unit to produce 20 to 25 
lb per hr of liquid oxygen for submarine use was 
designed, embodying the same thermodynamic prin¬ 
ciple as the Keyes unit, but incorporating somewhat 
different heat exchanger, fractionating tower, press¬ 
ure reducing mechanism and means of insulation. 
This unit was called the Latham unit. 11 ’ 12 Require¬ 
ments and design were the same as for the Keyes 
unit. The two most significant differences between 
the Keyes and Latham units were the method used 
for expansion and the method used for insulation. 


The Latham unit used a capillary tube rather than an 
expansion valve to allow for the Joule-Thomson 
refrigeration. The capillary expansion tube was so 
devised that when plugging by carbon dioxide oc¬ 
curred, it could be thawed out and the plug removed 
in a very short time by a simple thawing operation. 
The second most distinctive difference was that the 
Keyes unit was insulated in the usual manner by 
glass wool, whereas the Latham unit had all its cold 
elements encased in an 8-in. diameter steel cylinder 
with an integral vacuum jacket. The whole cold box 
was thus contained in a steel cylinder 5 ft high. The 
flow sheet for the Latham unit is given in Figure 6, 
and Figure 7 shows the unit itself without jacket. A 




















ARTHUR D. LITTLE-LATHAM UNIT 


43 



FREON (BI- 
REFRIGERATION 
UNIT 


Figure 5. Flow sheet of Keyes pump unit, Independent Engineering Co. 

















































































































































































































































44 


HIGH-PRESSURE CYCLES AND UNITS 



Figure 7. The A. D. Little—Latham liquid oxygen unit 
removed from the vacuum case. The expansion capillary 
is at the left. 


Steelman column was used for fractionation and 
proved to have a much lower capacity than design 
called for. The unit operated successfully during 
several test runs, but it was found that the effective 
life of the vacuum insulation was rather short and 
over a six months’ period, heat leak through the 
jacket rose from 80 Btu per hr to about 600 Btu per 
hr. 6 ’ 12 The unit was not developed beyond the test¬ 
ing stage since its production could not he main¬ 
tained at more than 12 lb of liquid per hr. Purity 
was obtained only with great difficulty due to the 
operation of the Stedman tow r er. 


44 TRAILER-MOUNTED GIAUQUE 
LIQUID OXYGEN PLANT— 

THE GIAUQUE UNIT 

A high-pressure plant suitable for both shipboard 
and trailer mounting was laid out on the cascade 
refrigeration principle and resulted in the Giauque 
unit. 13 ’ 1 * The unit was designed to produce 84 lb 
of liquid oxygen of 99.5% purity per hr. Its total 
weight, including trailer and all necessary equipment 
for operation, was 16,000 lb. It was designed to oper¬ 
ate using three refrigerants aside from air, namely, 
ethane, butane, and nitrogen. The air supply to the 
unit was 3,000 psi to start, and a lower pressure in 
the neighborhood of 2,000 psi during continuous 
operation. Several novel features were employed in 
the process, aside from the stepwise or cascade re¬ 
frigeration principle. A flow sheet for the process is 
given in Figure 8. 

A four-stage, high-speed, lightweight air compres¬ 
sor was developed for the plant 10 ’ 14 ’ 18 (see Chapter 5). 
The compressed air was taken through an aftercooler 
and water separator and then passed through potas¬ 
sium hydroxide solution for drying. The warm dry 
air was then sent to heat exchangers known as re¬ 
frigeration purifiers, thence to an ethane evaporator. 
After passing through the ethane evaporator, the 
air was returned and passed countercurrent to it¬ 
self in the refrigeration purifier. Thus, dry, warm air 
was cooled in the refrigeration purifier by the return 
stream of the same air after having been cooled to 
approximately —130 F by ethane refrigeration. In 
this operation the air was chilled to a low temperature 
whereupon all remaining water and any condensable 
hydrocarbons were precipitated in the exchanger, 
hence the term purifier. The temperature of the pure 
air from the refrigeration purifiers was within a few 
degrees of the temperature of the entering air. The 





















TRAILER-MOUNTED GIAUQUE LIQUID OXYGEN PLANT 


45 


LEGEND 



FOUR STAGE AIR COMPRESSOR 

STARTING UP PRESSURE 3000 LB / SO IN. 


Figure 8. Giauque mobile liquid oxygen unit flow sheet. 


refrigeration purifiers were switched at suitable time 
intervals and allowed to thaw for removal of water 
and hydrocarbons. The dry, clean air from the puri¬ 
fier was then passed through an exchanger counter- 
current to effluent nitrogen which was exhausted at 
this point. The cold air then entered the same ethane 
evaporator from which the refrigeration purifier ob¬ 
tained its activation. The air leaving this evapora¬ 
tor was at approximately —130 F and then passed 
through a nitrogen interchanger against the effluent 
from the fractionating column. This cold air was 
completely liquefied in the reboiler of the column and 
allowed to enter the column through a capillary ex¬ 
pansion valve. The ethane evaporator was fed with 
liquid ethane from an ethane compressor operated 
at a discharge pressure of 700 psi. The ethane was 
condensed at this pressure by butane which was con¬ 
tained in a separate cycle. The butane compressor 
operated with a discharge pressure of 176 psi and 
the gas was expanded to a butane evaporator, ex¬ 
tracting its heat for evaporation from the 7 psi 
ethane. Inlet pressure to the butane compressor was 
approximately 30 psi. High-pressure cold ethane gas 


was further cooled by an interchanger using evapo¬ 
rated ethane from the ethane evaporator at approxi¬ 
mately 21 psi, which was the intake pressure of the 
ethane compressor. 

Still a third refrigeration machine was planned for 
the unit. This refrigeration was to be accomplished 
by nitrogen. The overhead from the fractionating 
column was to be warmed up by passage through 
an interchanger, and compressed by a dry nitrogen 
compressor to about 100 psi. This high-pressure 
nitrogen passed countercurrent to the nitrogen in¬ 
take to the compressor, whereupon it was to be cooled 
to approximate liquid air temperature. The cold 
high-pressure nitrogen was then to be liquefied in 
the reboiler of the column and passed through an 
expansion valve, thereby supplying liquid nitrogen 
reflux to the top of the fractionating column. 

Such a compound refrigeration mechanism consti¬ 
tutes the cascade cycle and results in the most effi¬ 
cient use of energy to produce a given amount of 
refrigeration. Since the product was to be liquid 
oxygen, it was highly desirable to develop a system 
showing the greatest fuel economy. The liquid oxy- 














































































































46 


HIGH-PRESSURE CYCLES AND UNITS 



Figure 9. Interior view from front end of trailer after installation of air compressor and engine. 


gen produced by the unit could either he transported 
in hulk to other sites or to individual vaporizers 
where it could he vaporized to gaseous oxygen at 
either high or low pressure. 

The dry nitrogen compressor was not satisfactorily 
developed in time for incorporation in the unit. The 
final Giauque plant which was built and operated, 


omitted the nitrogen refrigerating cycle but did in¬ 
clude the ethane and butane compressors. The unit 
was also operated with Freon rather than with ethane 
in the ethane compressor and without making use of 
butane. 23 Thus, the system could he used either as 
laid out or with Freon in place of the ethane. The 
results of these modifications and test runs are cov- 

















TRAILER-MOUNTED KELLOGG OXYGEN PLANT 


47 



Figure 10. Rear platform and operating panel of liquid oxygen trailer unit. 


ered in various reports, especially No. 4141. Com¬ 
plete details regarding all equipment, design informa¬ 
tion, and test runs are given. 10 ’ 17 Figures 9 and 10 
are pictures of the Giauque unit. 

No production models were made as other liquid 
producing units were available, which operated with 
a less complex cycle and required fewer service sup¬ 
plies. The unit met design specifications. It was a 
successful development because it proved the oper¬ 
ability of the process. Features of the plant were 
used in the liquid producing plants which the E. B. 
Badger Company supplied to the Navy. 


4 5 TRAILER-MOUNTED GASEOUS 
OXYGEN PLANT—THE 
KELLOGG M-l UNIT 

A plant was laid out on the basis of a process 
using 3,000 psi pressure air to produce 1,000 cfh of 
high-purity gaseous oxygen. The plant was trailer- 
mounted and its total designed weight, including 
trailer, was 24,700 lb. 19 Figure 11 is a flow sheet 
of the M-l cycle. The original intention was to de¬ 
velop a low-pressure trailer-mounted plant and a 
high-pressure trailer-mounted plant, both to perform 




































48 


HIGH-PRESSURE CYCLES AND UNITS 


the same service. The M-7 plant was developed and 
operated successfully some time before the M-l plant 
was ready to run. The low-pressure M-7 cycle had 
many advantages, and after its reliability had been 
proved, work was stopped on the M-l plant. The 
M-l was never run as a complete unit but the cold 
box was operated with the use of high-pressure air 
from standard high-pressure compressor equipment 
until pressure test failure. 5 - 6 ’ 10 The M-l cycle per¬ 
mits production of gaseous oxygen delivered at high 
pressure without the use of chemicals for air cleanup. 
Figure 12 is a view of the trailer-mounted unit show¬ 
ing the compressor, engine, and intercooler equip¬ 
ment. 

The following description of essential features of 
the unit will he useful in understanding its operation 
in connection with the flow sheet of Figure 11. 

The refrigeration required for liquefaction is gen¬ 
erated by high-pressure Joule-Thomson or throttling 
expansion enhanced by Freon forecooling according 
to the familiar Linde cycle with forecooling. Joule- 
Thomson expansion is employed in one single stage, 
and the greater thermodynamic efficiency which is 
obtainable by stepwise expansion has been sacrificed 
in favor of simplicity. 

Water is removed from the air by condensation, 
where possible, and by activated alumina. Carbon 
dioxide is removed by precipitation and filtration, 
thus making the unit independent of chemical sup¬ 
plies, an advantage of very great value for mobile 
field units. 

The fractionation system embodies two towers, 
which, contrary to conventional installations, are side 
by side and not one above the other. Though the 
conventional tower arrangement means a simpler 
system, the M-l system is capable of comparable 
performance, and its lesser height is a controlling 
consideration for a mobile unit. 

Air Compression. Air is compressed in a high¬ 
speed, air-cooled, 6-cylinder, 4-stage air compressor 
which is driven by a similar high-speed air-cooled 
Lycoming internal-combustion engine. The air is 
delivered at 3,000 psi during the starting period, but 
the pressure is dropped back to 800 to 1,000 psi for 
normal steady operation. After each compression 
stage the compressed air is cooled in an Aerofin tube 
section directly against a blast of cooling air supplied 
by a Sturtevant blower. Means are provided after 
each stage of the Aerofin cooler to remove conden¬ 
sate from the compressed air. 

Water Removal. The compressed air leaving the 


aftercooler is then cooled by the high-level Freon 
system to some 20 F below room temperature, in 
order to condense more water from the air and make 
the duty for the alumina dryers smaller. This C-17 
air cooler (see Figure 11) is followed by a drip drum, 
and then by an air filter, G-9, in order to separate 
the condensed water from the air. 

The air then enters the activated alumina air dry¬ 
ers, G-4. Two dryers are provided so that one may 
be regenerated while the other is in service. The 
dryers are regenerated with waste nitrogen from the 
plant heated to 500 F by means of the engine ex¬ 
haust. This exhaust heater, B-l, can be by-passed 
so that cool waste nitrogen may he used to cool the 
dryers after regeneration. The dryers are set up on 
a 4-hr operating cycle; 2 hr are allowed for drying, 
1 hr for regenerating, and one for cooling. A timer 
and set of automatic valves have been incorporated 
into the dryer system so that the drying operation 
is fully automatic and requires no manual attention 
from the operators. 

Cooling. The dried air leaving the air dryers is 
then divided into two portions, one of which is cooled 
against the oxygen from the fractionation system, 
while the other is cooled against the waste nitrogen 
and forecooled against Freon from the low-level 
Freon system. 

The smaller portion of dry air enters the oxygen 
coolers (C-4A and C-4B) in which it is cooled coun- 
tercurrently with oxygen. The two exchangers are 
arranged to give an operating air temperature of 
—121 F between the two exchangers. This is done 
so that all of the carbon dioxide precipitation which 
occurs on cooling is concentrated in the C-4B ex¬ 
changer, which has straight smooth-bore tubes for 
the air passage, in order to avoid fouling the heat 
exchanger. The C-4A exchanger has more tortuous 
air passages, and, though it is a more efficient, com¬ 
pact exchanger, it is more susceptible to fouling with 
precipitated carbon dioxide. Therefore the combina¬ 
tion of exchangers is used in order to get a compact 
unit, where no precipitation of carbon dioxide may 
be expected, and a unit which will allow precipitated 
carbon dioxide to pass on to the filter in that portion 
where precipitation occurs. 

The cold air containing carbon dioxide goes to 
the G-7 filter after leaving the oxygen cooler C-4B. 
The bulk of the air leaving the G-4 air dryers enters 
the C-2 nitrogen precooler, where it is cooled against 
waste nitrogen. This air then flows through the C-l 
Freon forecooler, where it is cooled by low-level 




FILTERS 


TEMPERATURE — F 
6 AS FLOW SCFH 
ENGINE RPM 
PURITY % OXYGEN 


O ”. f9 VAIUEl 

PRESSURE LBS/SO IN. GAGE 


FREON COMPRESSOR 

DESIGN CONDITIONS ARE SHOWN IN FLAGS 


FREON COMPRESSOR 


Figure 11. The M. W. Kellogg Co. 1,000 cfh mobile oxygen unit, mechanical high-pressure system. 








































































































































































































































































































































































































Figure 12. Inside the compressor trailer of the M-l unit. Intercooler and aftercooler in the sheet metal duct with the 
compressor just beyond. Lycoming engine in right background. 







50 


HIGH-PRESSURE CYCLES AND UNITS 


Freon, and then flows through the C-5A and C-5B 
nitrogen coolers, where it is cooled against waste 
nitrogen. The nitrogen coolers C-5A and C-5B bear 
the same relation to each other as do the C-4A and 
C-4B oxygen coolers, namely the air temperature 
between these two units is controlled so that precipi¬ 
tation of COo occurs only in the C-5B unit, which 
is designed to allow the solid phase to pass through 
to the G-7 filter, hut which is not so compact a unit 
as the C-5A exchanger. The Freon forecooling, 
which is used to enhance the Joule-Thomson expan¬ 
sion refrigeration generated by the unit, is applied 
only to the portion of air flowing through the C-l 
Freon forecooler. 

Filtration of Carbon Dioxide and Expansion of 
Air. The two portions of feed air, which had carbon 
dioxide precipitated in the C-4B and C-5B exchang¬ 
ers, come together in the shell of the G-7 filter. This 
filter has a self-cleaning, rotating Cuno cartridge. 
Because it is self-cleaning only one such filter is 
needed, but because its use in this service was experi¬ 
mental, it is followed by the duplicate G-5 filters. 
These G-5 filters have a glass cloth filtering medium 
and are provided with thawing connections, so that 
they can he thawed alternately. 

The cold high-pressure air, after filtration, is then 
throttled from the operation pressure to 100 psi in 
the expansion valves. The two throttle valves will 
be used when expanding from the 800-psi operating 
pressure, but only one valve will be required when 
throttling from the 3,000-psi starting pressure. 

Though the high-pressure air was freed of carbon 
dioxide snow before expansion, more precipitation 
occurs on throttling. This snow, formed on throt¬ 
tling, is removed from the air stream in the G-8 
filter, which has a self-cleaning, rotary Cuno car¬ 
tridge. 

Fractionation of Air. The throttled, filtered air 
then enters the fractionation system, which consists 
of a high-pressure tower and a low-pressure tower. 
Part of the feed air enters the bottom of the high- 
pressure tower where it is separated into an overhead 
pure nitrogen vapor product, and a bottom of rich air 
liquid product. The refrigeration providing reflux 
for this tower is supplied by evaporation of liquid 
oxygen withdrawn from the low-pressure tower, and 
by heat exchange with the overhead nitrogen from 
the low-pressure tower. 

The overhead nitrogen vapors from the high-pres¬ 
sure tower are condensed in one section of the re¬ 
boiler of the low-pressure tower, and are then ex¬ 


panded to the top of the tower to he used as reflux 
for the enriching section of the tower. 

That part of the feed air which did not go to the 
high-pressure tower is condensed in the second sec¬ 
tion of the low-pressure tower rehoiler. This con¬ 
densed air joins the rich air bottoms from the high- 
pressure tower and the mixture is filtered in duplicate 
glass cloth filters, G-l, and then throttled to 25 psia 
and sent to the low-pressure tower as enriched liquid 
air feed. 

Liquid oxygen is withdrawn from the bottom of the 
low-pressure tower, then evaporates in one of the 
condenser sections of the high-pressure tower, thus 
providing reflux. The oxygen vapors so formed give 
up their refrigeration to part of the incoming air in 
the exchangers, and emerge at room temperature. 

Gaseous nitrogen is taken from the top of the low- 
pressure tower and is warmed slightly in a second 
condenser section in the high-pressure tower. The 
nitrogen then flows through C-5B, C-5A, and C-2, 
where it is warmed up to room temperature against 
feed air, but by-passes the C-l exchanger. The dry 
room-temperature nitrogen is used for regenerating 
the G-4 air dryers, by being sent through the B-l 
exhaust heater to the dryer for regeneration, or 
directly to the dryer for cooling. The room-tempera¬ 
ture nitrogen is also used to thaw the G-l and G-5 
filters. 

Compression of Oxygen. The atmospheric tem¬ 
perature and pressure oxygen from C-4A is com¬ 
pressed in four stages to 2,200 psi in a dry carbon¬ 
ring, non-lubricated compressor, being cooled after 
each stage of compression directly against cooling air 
in an Aerofin tube cooler. The compressed oxygen 
is filtered and charged into cylinders at 2,200 psi. 

Freon System. The prime purpose of the Freon 
system is to provide forecooling to the feed air in 
the C-l forecooler. Freon is vaporized at —20 F and 
atmospheric pressure in C-l, and the Freon vapors 
are then superheated in the C-3 Freon superheater 
before being compressed in the J-4 low-level com¬ 
pressor to the condensing pressure. The vapors are 
condensed in the C-l6 condenser at the expense of 
Freon liquid supplied by the high-level Freon system, 
and the condensate is subcooled in the C-3 super¬ 
heater and then expanded into C-l where it evapo¬ 
rates, supplying the forecooling duty to the process 
air. 

The high-level Freon liquid is condensed in the 
C-l5 air-cooled radiator, and is subcooled in the C-8 
exchanger. Part of this subcooled liquid is expanded 




THE AIR REDUCTION COMPANY UNIT 


51 


into the C-16 condenser where it evaporates in order 
to condense low-level Freon discharged from the 1-4 
Freon compressor. The rest of the liquid from C-8 
is expanded into the C-17 air cooler where it evapo¬ 
rates, cooling the process air and condensing some 
water out of the air. The high-level Freon vapors 
from the C-16 condenser and the C-17 air cooler 
join together, and are superheated in the C-8 ex¬ 
changer. 1 he superheated vapors are compressed in 
the J-3 high level Freon compressor and condensed 
in the C-15 radiator. 

A two-level, cascaded Freon system was chosen 
because it was desired to evaporate Freon at —20 F 
and cool the Freon system with 120 F ambient air. 
L nder these conditions, the compression ratio was 
too great to he handled satisfactorily in one stage. 

4 6 TRAILER-MOUNTED GASEOUS 
OXYGEN PLANT—THE AIR 
REDUCTION COMPANY 
UNIT 

A unit was built for the production of 400 cfh of 
high-purity gaseous oxygen and was mounted on a 
single trailer 16 ft long and 8 ft wide. The total 
weight of the unit, including trailer, was 13,000 lb. 
It was primarily intended to be a unit which could 
be assembled quickly from equipment already avail¬ 
able to the industry, and for the purpose of charging 
cylinders for use by the Army Engineers and the 
Air Forces. 20 ’ 21 ’ 22 Quick starting time was antici¬ 
pated and achieved. Figure 13 is a flow sheet of this 
unit and shows designed conditions for start-up oper¬ 
ation. Air pressure can he reduced during continuous 
operation. 

The operation starts at high pressure using a 
straight Linde system with Freon forecooling using 
air pressure of 2,000 psi. The high-pressure air 
passes over caustic potash in cylinders and thence to 
an alumina dryer. After cleaning, the air passes 
through an exchanger, is cooled by exhaust nitrogen 
product oxygen, and thence passes to a Freon fore¬ 
cooler where its temperature is dropped to about 
—25 F. From here it passes to another exchanger 
where it is further cooled by product oxygen and 
tower overhead. The high-pressure air is liquefied in 
the reboiler, subcooled by nitrogen overhead, and 
then expanded through a valve into the tower. The 
exhaust nitrogen is passed back through the heat 
exchanger system and part of it is used in a nitrogen 
heater to reactivate the alumina dryers. Oxygen gas 
from the reboiler is compressed by a three-stage oxy¬ 


gen compressor to 2,000 psi and is then passed over 
a water separator and drying equipment. The oxygen 
is dried by alumina which in turn is reactivated by 
warm dry oxygen heated by hot exhaust nitrogen. 
Brief specifications for the principal parts of the unit 
are shown below. 

Fractionation system 

Plate tower, 6-in diameter, 8 ft long, 24 trays 
3j/8-in. spacing. 

Refrigeration system 

Coiled tubes (5) in shell exchangers. Total sur¬ 
face, 100 sq ft; 4 in diameter by 60 in. Total 
weight, including forecooler, 250 lb. 

Freon condensing unit. 34-lip York unit. 
Weight, 100 lb. 

Air purification system 

3, 4.5 in. ID x 60 in. KOH scrubbers. Weight, 
380 lb. 

2, 4.5 in. ID x 60 in. alumina dryers. Weight, 
250 lb. 

Air compression system 

Rix three-stage, 50 cfm, 500 rpm, 2,000 psi, ver¬ 
tical air compressor. Weight, 3,500 lb. 

Air-cooled radiators. Freon cooler to cool air 
to 90 F. 

Oxygen compression and drying system 

Three-stage, 6.5 cfm, 250 rpm, 2,000 psia, ver¬ 
tical water-lubricated oxygen compressor. 

2-3 in. ID x 30 in. dryers. Weight, 60 lb. Re¬ 
generated by oxygen heated by exhaust- 
heated nitrogen. 

Miscellaneous 

Ford engine. 1,600-1,700 rpm, 57 hp. 

Lindsay-structure trailer, 12x15x11 ft. 
Weight, 6,000 lb. 

General 

Starting time, 4 hr at 1,500 to 2,000 psia. 

Running pressure, 500 to 700 psia. 

This unit was operated successfully but severe vi¬ 
bration caused by the air compressor made it desir¬ 
able to mount the unit on a skid for future experi¬ 
mentation. It formed the basis for the design of a 
production model built for the Navy by the E. B. 
Badger Company for liquid production. These pro¬ 
duction models, however, had additional features 
such as a packed rotating column which is believed 
to be advantageous for shipboard operation. Final 
production models made use of assembly line com¬ 
pressors rather than those used on the Air Reduction 
model. 





52 


HIGH-PRESSURE CYCLES AND UNITS 


O 



<u 

b£ 

X 

O 

<v 


o3 


C 

U 


o 


o 

fV 


< 

W 










































































































































































































































































PORTABLE UNIT FOR LIQUID OR GASEOUS OXYGEN PRODUCTION 


53 


1 he prototype truck-mounted unit was later dis¬ 
mounted and built on skids, and was revamped to 
produce liquid oxygen. Also, a liquid oxygen pump 
was added to compress liquid oxygen (previously 
vaporized and recondensed) and this eliminated the 
use of an oxygen compressor and oxygen-drying ap¬ 
paratus.-" Figures 14 and 15 show the skid-mounted 
plant. 

After improvements, made in the skid-mounted 
setup, this plant was used in part to provide perti¬ 
nent information for the large M-6 liquid oxygen 
plant. Studies in carhon dioxide filtration were car¬ 
ried out in the skid-mounted plant before they were 
applied to the M-6, and the use of caustic was elimi¬ 
nated by successful adaptation of filters. Details on 
the skid-mounted plant are as follows. 22 

Column Performance 



Run No. 1 

Run No. 2 

Air flow, standard cfm 

50 

70 

As gas producer 

Cubic feet oxygen per hour at 
99.5% purity 

310 

440 

Cubic feet oxygen per hour at 
99.0% purity 

350 

480 

Running pressure psi 

1,200 

1,000 

As liquid producer 

Lb O 2 per hr, air at 1,850 psi 


24 

(forecooled to —2 F) 



Lb 0 2 per hr, air at 2,000 psi 


33 

(forecooled to —55 F) 

Liquid oxygen purity, % 


99.5+ 

Starting time, hr 


1.5 


The above performance at 70 cfm is that of the 
entire plant as shown, with the exception of the en¬ 
gine and air compressor which are incapable of 
delivering more than 50 cfm of air. It was necessary 
to add 20 cfm of air to the compressor output to get 
the tests at 70 cfm rating. 

The forecooler refrigerator used in the setup shown 
is adequate for the purpose of making gas production 
at either rate, but is somewhat short of sufficient ca¬ 
pacity for best results when producing liquid oxygen. 

Refrigerator units 

Forecooler, York jkphp size, air cooled. 

Dehydrator, water-cooled Carbondale ^4-hp 
size, runs at half speed with hack pressure 
control to hold 32 F on evaporator. 

Engine 

Ford 95-lip industrial unit as assembled by K. 
R. Wilson Company, New York, drives all 
equipment. About 40 lip is used at 1,600 rpm 
to operate plant at 50 cfm of air flow. 


Compressor 

Rix vertical three-stage water-cooled 50 cfm at 
500 rpm to 2,000 psi. 

Operating Supplies Based on 70 cfm Air Flow 
(55 to 60 hp required) 



Per 24 hr 

Per 1 week 

If diesel drive 

operation 

operation 

Diesel oil, lb 

680 

4,100 

(based on Caterpillar D4600) 



If gasoline engine drive 



Gasoline, gallons 

140 

980 

(based on Ford consumption) lb 

840 

5,880 

Potash, lb 

10 

70 

Engine oil, gallons 

V 2 

3/4 

Compressor oil, gallons 

'A 

1 

Approximate Weights 


Skid plant as shown in Figure 

14 

Pounds 

Column skid, including column and liquid pump 

2,500 

Potash tube—dryer skid 


1,000 

Refrigeration unit skid 


400 

Ford power unit 


1,400 

Rix compressor 


4,000 

Total 


9,300 


4 7 PORTABLE UNIT FOR EITHER 
LIQUID OR GASEOUS OXYGEN 
PRODUCTION—THE 
LEROUGET PLANT M-31 

A plant was built on the basis of a high-pressure 
cycle employing low-level refrigeration by direct air 
expansion and high-level refrigeration by nitrogen 
expansion in an expansion engine (Figure 14). This 
cycle, known as the LeRouget cycle, had been built 
and operated in Great Britain, but was not tried out 
in the early stages of the oxygen program. It was 
later built in the Central Engineering Laboratory 
of this section in the early part of 1944 and was de¬ 
signed to produce 50 lb of liquid oxygen per hr. 5 ’ 10 ’ 19 
It was visualized that this cycle offered the best pos¬ 
sibility for efficient production of either liquid or 
gaseous oxygen of high purity. Such a unit was 
coming to he of interest to the Air Forces because 
it was felt that if liquid oxygen could he produced 
and stored at times when empty gas cylinders were 
not available, considerable time could be saved and 
convenience attained in aircraft oxygen supply. Fur¬ 
thermore, although the Air Forces was committed 
to the use of gaseous oxygen, it was becoming in¬ 
creasingly apparent that liquid oxygen could and 
should eventually be the means for using oxygen 
aboard aircraft. In addition to the desirability of 
developing an efficient plant for the production of 





54 


HIGH-PRESSURE CYCLES AND UNITS 



Figure 14. Air Reduction Co., Inc., skid mounted unit. 


liquid oxygen or gaseous oxygen (with the aid of a 
liquid oxygen pump, thus eliminating the use of a 
gaseous oxygen compressor), there were two other 
objectives in mind. First, to demonstrate the LeRou- 
get cycle as a practicable method for generating 
liquid oxygen ; and second, to develop a system for 
the mechanical removal of water and C0 2 from the 
compressed air used in a high-pressure oxygen gen¬ 
erator. The first objective was definitely reached, 
and the second objective approached closely enough 
to justify the hope that it can he attained after a 
reasonable' amount of further experimentation. 

The distinctive feature of the LeRouget cycle is 
the use of expansion engines in the effluent nitrogen 
stream to produce a portion of the refrigeration. The 
remaining refrigeration is obtained by Joule-Thom- 
son expansion of the high-pressure air. Auxiliary 


forecoolers and heat exchange between the forecooler 
and the warm air stream are eliminated. To obtain 
refrigeration from the expansion engines, the frac¬ 
tionating tower, including the low-pressure tower of 
the double column, must operate at an appreciable 
back pressure. In the laboratory unit the pressure on 
the tower was about 50 psi. The high tower pressure 
leads to two minor disadvantages: the fractionation 
per tray is somewhat reduced, and if liquid oxygen 
is made, it suffers a flash loss of approximately 6%. 
If the unit is operated to produce high-pressure gas 
directly, and it can he built to do so if a liquid pump 
is installed, there is no flash loss. The additional 
fractionation called for by the high distillation pres¬ 
sure can be supplied by a few additional trays. 

The unit built and operated in the Central Labo¬ 
ratory at first was equipped with a single tower. 





















55 


PORTABLE UNIT FOR LIQUID OR GASEOUS OXYGEN PRODUCTION 



Figure 15. Air Reduction Co., Inc., skid mounted unit. 


Satisfactory cycle operation was obtained, and then 
a double column was installed to increase the yield 
and production of oxygen without increasing the 
amount of air supplied to the unit. The unit was 
not ecpiipped with its own compressor, and air at 
3,000 psi was taken from laboratory supply service. 

A LeRouget cycle is ideal for application of the 
small, high-speed, rotary expander described in a 
later chapter. The small expander can only operate 
on clean gas, and the nitrogen effluent of the LeRou¬ 
get cycle is completely free of water, oil, and C0 2 . 
Also, the temperature level of the expansion step 
(—45 to —100 F) is warmer than that in the low- 
pressure units described in Chapter 2. Because of 
the higher temperature, lubrication of the expander 
becomes easier. 

The operation of the M-31 unit was very success¬ 
ful as far as the cycle and process were concerned. 10 
All operating difficulties originated in the C0 2 clean¬ 
up system. As long as C0 2 could he rejected by the 
unit, operation was smooth and regular. The liquid 
production rate was 43 lb per hr of 99.4% oxygen, 
after flash, from 408 lb per hr of air. A flow sheet 
showing operating data is given in Figure 16. 

The mechanical cleanup of FLO and C0 2 in the 


unit is accomplished by the following method. The 
water is precipitated as ice in switching exchangers. 
The ice is collected in one exchanger, which is de- 
rimed when the other exchanger is put into service. 
The exchangers are switched on a three- or four-hour 
cycle. No trouble with water removal was expe¬ 
rienced during many hours of operation and this 
portion of the mechanical cleanup system is entirely 
satisfactory. 

The removal of C0 2 mechanically in the M-31 unit 
proved to he more difficult, and much experimental 
work has been done to find a solution to the problem. 
The elements of the solution are at hand, as the last 
run lasted 200 hr and was terminated by a plugged 
line. 

The C0 2 removal method is based on the filtra¬ 
tion of solid C0 2 from the various liquid, or partially 
liquid, streams that enter and leave the double frac¬ 
tionating column. The septum used in the filters is 
A A Fiberglas, a new development in glass, which is 
a felted cloth consisting of very fine (0.5 /<) glass 
fibers. Several layers of the material can he used 
without appreciable pressure drop, and the material 
will remove particles as fine as are present in ciga¬ 
rette smoke. The main problem in constructing the 
















56 


HIGH-PRESSURE CYCLES AND UNITS 



Figure 16. Central Engineering Laboratory liquid oxygen unit M-31. 





















































































































































































































































































PORTABLE UNIT FOR LIQUID OR GASEOUS OXYGEN PRODUCTION 


57 


filter is to seal the Fiberglas at the ends of the filter 
so that particles of C0 2 cannot short-circuit. This 
problem has not been completely solved. 

From the results obtained thus far on solid C0 2 
equilibrium with air, 10 in which the dew points of 
C0 2 in high-pressure air have been measured, it 
appears that the high-pressure air at 3,000 psi does 
not precipitate C0 2 in the M-31 unit during the 
cooling step. At the Joule-Thomson expansion, 
however, where the pressure is suddenly reduced 
from 3,000 psi to 300 psi, copious precipitation of 
C0 2 occurs, both from the reduction of pressure and 
from the reduction of temperature. A filter (G-2) 
immediately following the throttle valve removes the 
C0 2 precipitated in the expansion. Approximately 
90% of the C0 2 is removed in the filter. The air leav¬ 
ing filter G-2 is partially liquefied, and liquefaction 
is completed in the reboiler of the high-pressure 
tower. In the high-pressure tower the feed is split 
into liquid bottoms, or rich air, and liquid nitrogen 
reflux for the low-pressure tower. Since the latter 
stream is condensed from the vapor phase, it con¬ 
tains no C0 2 , and the C0 2 remaining in the air after 
the filter G-2 is concentrated several-fold in the rich 
air. The concentration in this stream exceeds solu¬ 
bility, and the excess precipitates in a form that tends 
to accumulate on the walls of the pipes and in fittings 
and valves. Accordingly, a second filter, built in par¬ 
allel duplicates, is installed in the rich air line. These 
are the G-3 filters. Finally, when the pressure on 
the rich air is reduced to the pressure existing in 
the low-pressure tower, additional C0 2 is deposited, 
which is prone to plug the throttle valve and the pipe 
leading from the valve to the tower. A third filter, 
labeled G-6, has been inserted in this line. 

With all the filters in operation, a successful run 
of 200 hr has been made. The run terminated, how¬ 
ever, when a plug formed in the line between the 
main expansion valve and the pressure reduction 
valve in the line from the high-pressure reboiler. 

The mobile oxygen plant of the future may well be 
an M-31 type of unit, using a diesel-driven, direct 
piston connected, high-pressure air compressor, a 
liquid oxygen pump, small rotary expanders, and 


utilizing the method of mechanical cleanup as just 
described. Such a unit should be extremely attrac¬ 
tive as a small, lightweight, efficient unit capable of 
producing high-pressure gaseous or liquid oxygen. 

Figure 16 gives the flow sheet and operating con¬ 
ditions for a 200-hr run. Production and all other 
pertinent data are indicated on the flow sheet. The 
plant has had many hours of successful continuous 
operation and has also demonstrated its ability to 
operate intermittently over extended periods of 
time. 7 ’ 8 ’ 9 ’ 10 Figures 17 and 18 are pictures of the 
M-31 unit without the high-pressure air compressor. 



Figure 17. M-31 construction. Expander installation. 

















58 



HIGH-PRESSURE CYCLES AND UNITS 


Figure 18. M-31 completed unit, 














Chapter 5 

AIR COMPRESSORS AND EXPANSION ENGINES 

By /. H. Rushton 


51 THE COMPRESSOR PROGRAM 


A x investigation was made to determine 
. whether any standard machines were avail¬ 
able for air compressors which would have a very 
low weight capacity ratio. This survey work took 
into account all types and sizes of reciprocating 
air compressors, water-cooled and air-cooled, oil- and 


lb per cfm and covered a range of 3.27 to 30.0 as 
shown in Table 1. Very little difference was found 
in operating efficiency as judged from published in¬ 
formation ; the air-cooled units, although lighter, did 
require more energy output. No equipment found 
in this class utilized the crosshead-type design, a 
prerequisite to operation with controlled lubrication 
or even oil-free operation. More important, no equip- 


Table 1. Tabulation of various stock compressors.* 


Manufacturer 

Design 

discharge 

pressure 

Piston 

diplacement 

cfm 

W eight 

Lb cu ft 
displacement 
per min 

Comments 

\\ orthington 

100 

83 

900 

11.1 


Worthington 

100 

445 

2,700 

6.06 


Gardner Denver 

100 

32 

330 

10.0 


Gardner Denver 

100 

367 

2,510 

6.8 


Curtis 

100 

9.8 

135 

13.6 


Curtis 

100 

53 

425 

8.0 


Ingersoll-Rand 

100 

6 

180 

30.0 

Estimated 

Ingersoll-Rand 

100 

52 

800 

16. 

Estimated 

Quincy 

100 

23 

275 

12. 


Quincy 

100 

80 

525 

6.5 


Davey 

100 

133 

555 

4.16 


Davey 

100 

443 

1,500 

3.40 


Schramm 

100 

124 

600 

4.85 


Schramm 

100 

601 

1,960 

3.27 


Clark 

100 

296 

500 

1.7 

(Clark proposal) 

W orthington 

250 

7.7 

190 

25.0 


Worthington 

250 

67.0 

730 

10.9 


Ingersoll-Rand 

250 

6.5 

200 

31.0 


Ingersoll-Rand 

250 

41 

600 

14.0 


Quincy 

250 

5 

140 

28.0 


Quincy 

250 

22 

270 

12.3 


Gardner Denver 

250 

40 

750 

18.8 


Gardner Denver 

250 

92 

1,650 

17.4 


Clark 

250 

190 

500 

2.63 

(Clark proposal) 

Worthington 

500 

6.1 

185 

30.0 


Worthington 

500 

80 

1,025 

12.8 


Ingersoll-Rand 

500 

7.4 

250 

34 


Ingersoll-Rand 

500 

15.2 

520 

34 


Quincy 

500 

4.2 

140 

33.5 


Quincy 

500 

20.8 

270 

12.9 


Clark 

600 

190 

600 

3.13 

(Clark proposal) 

Ingersoll-Rand 

1,000 

29 

660 

23 

4i x 14 x 4, Type 20 

Ingersoll-Rand 

1,000 

50 

825 

16.5 


Rix 

1,000 

15 

550 

36.0 



* Data taken from manufacturers’ catalogs, 1941. 


water-lubricated, and portable and stationary equip¬ 
ment. 1 ’ 2 - 11 ’ 12,16 ’ 17 ’ 19 ’ 23 For compressors under 100 hp 
and working at discharge pressures not over 300 psi 
(the so-called portable or small units), it was found 
that the weight to displacement ratio averaged 13.31 


ment was found for operation with either water as 
lubricant or else no lubricant at all. (Exceptions to 
this were two manufacturers’ lines of heavy horizon¬ 
tal stationary low-pressure units using carbon rings 
and water lubrication.) 


59 







60 


AIR COMPRESSORS AND EXPANSION ENGINES 


Turbo or centrifugal compressors were found to 
be available in extremely high-capacity, low-ratio 
units, that is, 5,000 cfm operating at a maximum ratio 
of compression of 3.0. One manufacturer stated that 
given two years, be could develop a unit having a 
capacity as low as 3,000 cfm for an overall ratio of 
7 in a multistage unit. 

Rotary compressors of the type known as displace¬ 
ment blowers were found to be limited in compres¬ 
sion ratio, inefficient, and unsatisfactory for our pur¬ 
pose. A type of modified rotary compressor, wherein 
actual internal compression took place, was found to 
hold great promise. This compressor, known as the 
Lysholm type, was then being manufactured in large 
sizes in this country under foreign licenses by the 
Elliott Company of Jeannette, Pa. It was thought 
that a machine of this type could he developed in a 
two-stage unit having a capacity of as low as 200 
cfm for an overall ratio of not more than 6, although 


lines: a rotary Lysholm type or a two-stage, air¬ 
cooled, high-speed, crosshead-type, reciprocating ma¬ 
chine. 

For high-pressure service as required by the high- 
pressure Giauque unit (Chapter 4) there was nothing 
available in lightweight equipment to meet the fol¬ 
lowing desired specifications: 

Capacity, approximately 110 cfm. 

Discharge pressure, approximately 3,000 psi. 

Weight, not more than 800 lb. 

Lubrication, oil. 

A development program was initiated to produce 
a compressor for such service. 

As a result of this survey for the requirements of 
the projected service units, it was decided to design 
and build the air compressors described in Table 

O 6,10,11 


Table 2. Air compressors. 


Description 

Capacity, cfm 

Pressure, 

psi 

Projected 
weight 
without 
drive, lb 

Size 

6-cylinder reciprocating oil, lubricated, 
air-cooled, 55 hp 

200 

90 

600 

33 x 30 x 24 in. 

6-cylinder, reciprocating non-lubricated, 
air-cooled, 50 hp 

200 

90 

650 

36 x 30 x 24 in. 

Rotary, high-speed (Lysholm) 
oil-cooled, 60 hp 

200 

90 

50 

24 x 18 x 12 in. 

6-cylinder, reciprocating oil-lubricated, 
air-cooled, 60 hp 

100 

3,000 

600 

33 x 30 x 24 in. 

4-cylinder, reciprocating combination 
engine and compressor 

35 

150 

420 

33 x 30 x 25 in. 

Vertical, low-speed reciprocating 
diesel-driven, 500 hp 

2,000 

90 


12 x 9 x 4 ft 

Vertical, medium-speed, diesel- 
driven, 500 hp 

1,000 

600 


12 x 12 x 4 ft 


this size would probably be the smallest practical unit, 
according to the designers, and would require con¬ 
siderable development work. 

Summing up, there was found to be no commer¬ 
cially available compressor which would meet the 
following specifications: 

Capacity, approximately 200 cfm. 

Discharge pressure, approximately 100 psi. 

Weight, not more than 700 lb. 

Lubrication, controlled or non-lubricated. 

It was thought likely that a compressor could be 
developed for these specifications along either of two 


5 2 SIX-CYLINDER LOW-PRESSURE 
OIL-LUBRICATED AIR 
COMPRESSOR 

An air compressor was desired with a capacity 
of 200 cfm delivered at 90 psi for use with the 1,000 
cfh oxygen plants. Since these plants were to be 
mounted on trucks, it was desirable to have a com¬ 
pressor of as light weight as possible. The power 
for such a compressor was felt to be best obtained 
by the use of aircraft engines of the Franklin or 
Lycoming types. These engines were also in use by 
the Services for tanks and other field uses. The 






OIL-LUBRICATED AIR COMPRESSOR 


61 


speed of such a power device made it desirable to 

pressor. A number of these models were built but 

develop a compressor that could be directly connected 

they 

never entered commercial production because 

or at most to have but a small speed reduction from 

of the development of the dry air compressor, which 

that of the prime engine. The crankcase of a com- 

was 

built on the same 

principle as this one, except 

mercial aircraft engine was used as a basis for the 

that oil lubrication was 

eliminated by the use of car- 

Table 3. Specifications 4% in. x 4 in. two-stage six-cylinder horizontal opposed oil-lubricated Clark air compressor. 

Compressor end 




Design operating conditions 




Gas to be compressed 


Air 


Quality 


Saturated at 14.7 psia and 95 F 

Maximum suction temperature F 


120 


Suction pressure psia 


14.7 


Discharge pressure psia 


104.7 


Staging data 


First 

Second 

Suction temperature F 


120 

140 

Suction pressure psia 


14.7 

36.7 

Discharge pressure psia 


41.7 

104.7 

Discharge temperature F 


300 

325 

Dry volume scfm 


189 

189 

Wet volume scfm 


200 

193 

Inlet cond. cfm 


223 

89.1 

Compressor specifications 




Type 


Air-cooled horizontal opposed 

RPM 


1715 


Stroke in. 


4.0 


BHP required 


59.0 


No. of compressor cylinders 


6 single-acting 


Type cylinders 


Finned chrome-plated bore 

Type cooling 


Air forced ventilation 

Type piston 


Crosshead guided 


Rings 


American hammered metallic 

Stage 


First 

Second 

No. of compressor cylinders 


4 

2 

Bore in. 


4.875 

4.875 

Stroke 


4.0 

4.0 

Piston displacement cfm 


296 

148.0 

Approx, vol. eff. 


75.3 

60.1 

Est. capacity cfm inlet 


223 

89.1 

Est. capacity scfm wet air 


200 

193 

Overall length 


33 %g in- 


Overall width 


43 in. 


Overall height 


24 in. max. 


Weight complete, less frame 


650 lb 


Horizontal distance required to pull compres- 


Cylinder must be removed first 

sor pistons from CL of compressor 


25 in. from CL required 


Accessories supplied 

Intake air filters low stage 
Manifold low-stage discharge 
Manifold high-stage inlet 
Manifold high-stage discharge 
Shaft half coupling (Thomas) 
Cooling air shrouding 
Flywheel Fan 

Air filters Crosshead breathers 
Mounting supports and mount 


air compressor. 1 The compressor specifications are 
given in Table 3. Figure 1 shows the resulting com¬ 
pressor with direct-connected drive. Figures 2 and 3 
are experimental characteristic curves for this com- 


bon rings. This oil-lubricated compressor develop¬ 
ment proved to be extremely useful as a background 
for tbe final nonlubricated air compressor to be de¬ 
scribed next. 11 





62 


AIR COMPRESSORS AND EXPANSION ENGINES 



Figure 1. Clark 4 % in x 4 in., 6-cylinder. 2-stage, “oily" 
air compressor driven by Franklin engine. 


3 5 LOW-PRESSURE DRY AIR 
COMPRESSOR 

This compressor was built on a Lycoming engine 
crankcase such as was used for tank propulsion. In 
its final form it was used for the low-pressure mobile 
1,000 cfh oxygen plants (M-7, M-7AT, and the LP 
plants), and a number of these compressors were 
manufactured by Clark Bros. Inc. Figure 4 shows 
this dry air compressor, and in Table 4 are the prin¬ 
cipal specifications. Specifications regarding capacity 
and stage data are the same as for the oil-lubricated 
compressor described in Table 3. 

It is of a special interest to note that this machine 
gives very long life, running without lubrication, and 
the carbon rings are capable of standing severe oper¬ 
ating speeds of 1,030 ft per min corresponding to a 
crankshaft speed of 1,600 rpm. These nonlubricated 
machines have run under test for continuous operat¬ 
ing periods of 150 hr, and have operated for upwards 
of 1,000 hr before complete overhauling. Conven¬ 
tional oil-lubricated compressors usually operate at 
piston speeds of 800 ft per min. Using the higher 
speed in this machine has enabled the realization of a 



PER CENT STROKE 


Figure 2. Clark 4^8 in. x 4 in., 2-stage, horizontally op¬ 
posed air compressor, 1,750 rpm. 



Figure 3. Florizontal opposed 4 % in. x 4 in., 2-stage 
compressor, capacity vs rpm 90 psi discharge pressure. 


low weight per unit capacity of 3.7 lb per cu ft per 
min discharge. 

Complete details regarding construction are cov¬ 
ered in various progress reports. 3 - 4 ’ 5 ’ 6 ' 8 Probably the 
most important development in the design of this 
compressor has to do with the compressor cylinder. 
Its construction is illustrated in Figure 5. 

Performance tests were run at various crankshaft 
speeds between 1,000 and 2,000 rpm and discharge 
pressures between 40 and 120 psi. (Figures 6 and 7.) 
The compressor was designed for 220 cfm and this 
was attained at 1,600 rpm. (Figure 8.) The maxi¬ 
mum speed at which the compressor should operate 
is 1,850 rpm with a maximum discharge pressure 
of 110 psi. Pressures in excess of 110 psi result in 
discharged temperatures which are too high for long 
valve life. Further, for higher speeds and pressures 
the bearings are loaded beyond their design. Oil- 


















63 


DRY AIR COMPRESSORS 



Figure 4. Six cycle, two-stage, low-pressure, dry air compressor. 


Table 4. Specifications Model DHO-6-2 Clark Dri-Air compressor. 


Type: 
Model: 
Stages 


6-cylinder, two-stage, horizontal opposed cross-head nonlubricated 
DHO-6-2 


First 


Second 


No. of cylinders 

4 

2 

Bore 

5 14 in. 

5 J4 in- 

Stroke 

3 % in. 

3 Vs in. 

Inlet pressure psia 

14.7 

33.0 

Discharge pressure psia max. 

35.0 

114.7 

Discharge temp. F 

255 

345 

RPM 

1600 


Capacity at inlet conditions 

224 


BHP required 

Material specifications 

61 


Cylinders 

Highly polished chrome-plated C.I. 

Pistons 

Aluminum castings 


Piston rings 

3-segment Graphitar #2 (butt joint) 

Guide rings 

3-segment Graphitar #2 (butt joint) 

Dimensions 



Installation drawing 

108-288 


Overall height 

39 >4 in. 


Overall length 

41 )4 in. 


Overall width 

60 in. 


Weight 

900 lb 


Equipment supplied 

Oil pressure and temperature gauges, 
oil filter, “one shot” lubricator, air intake 


filters, and interstage 

manifolds 
























64 


AIR COMPRESSORS AND EXPANSION ENGINES 




Figure 5. Cross-section compressor cylinder Clark Dri- 
Air compressor. 



Figure 6. Two-stage Dri-Air compressor—speed vs 
horsepower. 



Figure 7. Two-stage Dri-Air compressor—discharge 
pressure vs horsepower. 












































































































































































ROTARY TWO-STAGE AIR COMPRESSOR 


65 



Figure 8. Two-stage dry compressor—capacity vs speed; 
100-lb discharge pressure suction conditions. 


cooling temperature should not exceed 200 F. Al¬ 
though the machine has operated with unexpectedly 
long life for carbon rings at the severe operating 
speeds, there is still a lot of further development 
which should be done to increase the life of the unit 
and allow it to perform more efficiently. It is antici¬ 
pated that this machine could be developed to a much 
higher degree than in its present form. Power re¬ 
quirements for the compressor at different speeds and 
at different discharge pressures are shown in Figures 
6 and 7. Further attention to the details of construc¬ 
tion of the carbon rings and guides would undoubt¬ 
edly result in a decrease in power requirements. The 
power requirements for the nonlubricated compres¬ 
sor are considered to be modest, considering the 
weight and portability features of the unit when op¬ 
erating at a discharge pressure of 100 psi and 1,600 
rpm. While compressing 224 cfm, the brake horse¬ 
power is 61 hp. 

5.4 ROTARY TWO-STAGE ELLIOTT- 
LYSHOLM AIR COMPRESSOR 

In an attempt to achieve extreme compactness and 
lightness in weight, considerable attention and ex¬ 
perimentation was given to the Lysholm-type rotary 


compressor. 9 - 18,19 ' 20 ’ 21 Such a compressor was laid 
out to have a capacity of 200 cfm of air at one at¬ 
mosphere pressure and 60 F delivered at 90 psi. 
Such a compressor was to be nonlubricated and to 
run at high speed, being direct-connected to a gaso¬ 
line-driven engine or, if desired, to an electric motor. 
The total weight of such a unit was anticipated to be 
approximately 150 lb with the intercoolers. Such a 
machine was built, tested, and operated for a short 
period of time and was finally delivered to the Navy 
Department, Bureau of Ships, for use in the Engi¬ 
neering Experiment Station in Annapolis. 34 The 
final unit was somewhat cramped in design and the 
Elliott Company, builders of the unit, felt that the 
compressor should be redesigned to allow a little 
more room for bearings and other mechanical ele¬ 
ments so that it would not be operating at such criti¬ 
cal limits as in this first development model. It was 
felt that redesign of this nature would be necessary 
before the unit should be produced in quantity for 
use by the Services. At the time this decision was 
reached (July 1944), it was considered inadvisable 
to continue the development inasmuch as 8 to 10 
months’ time was estimated before an improved 
model could be built and that this would be too late 
to be of use in World War II. 

A description of the unit follows. 

Design Operating Conditions 
200 cfm of dry air at 14.7 psia and 60 F 
Suction temperature, 1st stage: DOF 
Suction temperature, 2nd stage : 120 F 
Suction pressure: 1 atm abs 
Discharge pressure: 90 psi 
Gas to be handled: Air 
Moisture content of inlet air: Assume 
saturation at 14.7 psia, 90 F 

An assembly drawing of the original design is 
shown in Figure 9, and Figures 10 and 11 show 
photographs of the complete unit and rotors as finally 
assembled. 9 

The compressor is of the Lysholm type with two 
stages. Both stages are connected to a common drive 
shaft through a gear case built as an integral part of 
the unit. The two stages are of identical design, 
except for length and rotational speed. The high- 
pressure stage is 0.86 times the length of the low- 
pressure stage and turns at half the speed (10,000 
rpm), giving a displacement of 115.2 cfm as com¬ 
pared with the low-pressure displacement of 297.2 
cfm. 

The input shaft turns at 2,000 rpm, driving two 




66 


AIR COMPRESSORS AND EXPANSION ENGINES 



Figure 9. Two hundred-cfm Lysholm compressor. 



Figure 10. Lysholm compressor—weight 165 lb, 180 to 
200 scfm at 90 psi. 


countershafts through a bullgear-spur pinion com¬ 
bination at 2,590 rpm and 5,180 rpm. Identical in¬ 
ternal gears on the countershafts mesh with the male 



Figure 11. Lysholm compressor rotors. 


timing gears to produce the 10,000 and 20,000 rpm 
speeds. 

The inlet and discharge ports are all essentially 
radial. 

Each compressor stage has a cooling jacket which 
is supplied with oil at 10 psi pressure from an oil 
pump built onto the gear case. This same oil pump 
supplies oil to wicks and drip feed for bearings and 
to spray jets for lubrication of the ground gears. The 
bottom of the gear case is utilized as a sump for the 
oil system. The oil is circulated through a filter and 
an oil cooler (water supplied), both incorporated in 
the complete unit. 









































































































































































































































ROTARY TWO-STAGE AIR COMPRESSOR 


67 


Ball bearings were used throughout the machine. 
Angular contact bearings were used to take the thrust 
in the compressor stages and to locate the rotors 
axially. The bearing life was designed to be 
50,000 hr. 

1 he total weight of the unit, as assembled at the 
end of the testing period, was 165 lb 29 (excluding the 
intercooler). See Figure 10. 

1 he testing program as originally intended was 
directed mainly toward the testing of thermodynamic 
performance and mechanical endurance of the ma¬ 
chine, but due to the multitude of mechanical diffi¬ 
culties encountered, it soon took the form of rede¬ 
sign in part, or improvement of the original design. 

During the testing period several performance tests 
were run on each individual stage, and on the unit 
as a whole. Figures 12, 13, 14, 15, 16, and 17 give 

> 



1.4 1.8 2 2 2.6 3.0 3.4 

PRESSURE RATIO* P 


Figure 12. Two hundred-cfm Elliott Lysholm com¬ 
pressor—low-pressure stage adiabatic efficiency test. 



Figure 13. Two hundred-cfm Elliott Lysholm com¬ 
pressor—low-pressure stage volumetric efficiency test. 


D 



Figure 14. Two hundred-cfm Elliott Lysholm com¬ 
pressor—high-pressure stage adiabatic efficiency test. 


performance curves for each individual stage and for 
the complete unit. 

1 he best data indicate the following performance 
for operation at the design conditions. 

182 cfm of dry air, at 14.7 psia and 60 F (minus ap¬ 
proximately 10 cfm for leakage through the seals) 
Moisture content assumed to be such that there is 
saturation at 14.7 psia and 90 F 
Shaft input: 54.8 hp at 2,000 rpm 
Adiabatic efficiency: 64.7% 

Inlet air, 1st stage: 14.7 psia and 120 F 
Inlet air, 2nd stage: 120 F 
Discharge air: 104.7 psia 


O 



Figure 15. Two hundred-cfm Elliott Lysholm com¬ 
pressor—high-pressure stage volumetric efficiency test. 



23456 789 

PRESSURE RATIO- /° 


Figure 16. Two hundred-cfm Elliott Lysholm com¬ 
pressor unit; volumetric and adiabatic efficiency speed 
vs pressure ratio, 2,000 rpm. 



PRESSURE RATIO -P 


Figure 17. Two hundred-cfm Elliott Lysholm com¬ 
pressor—complete unit; volumetric and adiabatic effi¬ 
ciency based on theoretical displacement of low-pressure 
stage. 






















68 


AIR COMPRESSORS AND EXPANSION ENGINES 


To bring the output up to the required 200 cfm 
of air, the speed would have to he increased from 
2,000 rpm to approximately 2,300 rpm. 

The maximum operating condition tested for the 
complete unit is as follows. 

211 cfm of gas mixture (minus approx. 10 
cfm for leakage through seals) 

Shaft speed: 2,000 rpm 
Hp input: 59 hp 
Adiabatic efficiency: 63% 

Inlet air: 13.3 psia, 80 F 
Discharge air: 103 psia, 380 F 
Pressure ratio: 7.75 
Intercooling to: 80 F 

The complete unit gave a peak adiabatic efficiency 
of 68% at a pressure ratio of 5. 

The adiabatic efficiency quoted is based on one- 
stage adiabatic compression from 13.3 to 103 psia. 

At the maximum operating condition quoted above 
the low-pressure stage operates at a 3.3 pressure 
ratio and the high-pressure stage at 2.4. This checks 
very closely with the values estimated in the design. 

At these pressure ratios the adiabatic efficiencies 
are 56% and 52% for low- and high-pressure com¬ 
pression respectively (Figures 12 and 14). 

The low-pressure compressor has a peak adiabatic 
efficiency of 64% at 2.3 pressure ratio; and the high- 
pressure compressor, 56% at 1.9. 

The efficiencies given for the separate stages are 
taken from test runs made with atmospheric inlet 
conditions for both stages, and only one stage as¬ 
sembled on the gear case at a time. The values given 
may be somewhat low since in this way more of the 
gear-case power loss is contributed to each stage 
than would he the case in the complete unit. The 
particular tests from which these efficiencies were 
taken are the best results obtained for each stage. 

In an attempt to measure the amount of leakage 
through the seals in the complete unit, it was found 
that at least 7 cfm of free air leaked when the unit 
ran at 2,000 rpm with a discharge pressure of 103 
psia. 

Any Lysholm compressor is inherently noisy. The 
air-noise is of a rather high pitch (approximately 
1,000 and 500 db) due to the high rpm of the rotors. 
A silencer and filter were used on the inlet, and 
the discharge was piped to the outside of the labora¬ 
tory. This reduced the air-noise very considerably. 
The mechanical noise from the gear case is quite 
appreciable. 

It was decided that much of the remaining air- 
noise was transmitted through the piping and the 


intercooler, and an attempt was made to improve 
the condition by covering all piping with a heavy 
layer of glass wool. The glass wool lagging cut down 
the noise from 102 to 95 db as measured with a 
sound-level meter. (The pick-up was placed at a 
distance of 8 ft from the compressor.) The noise 
appeared now to he mainly mechanical, and the noise 
of the machine was sufficiently low to permit conver¬ 
sation without much difficulty. 

To summarize the performance tests, which show 
that at 2,000 rpm the machine will supply 200 cfm of 
free air at 103 psia when the inlet air is at 13.3 psia 
and 80 F, the horsepower input required is 54 with 
intercooling at 80 F. In the final report on the unit 11 
are listed definite proposals for further work on such 
a compressor suitable for production. 

5 5 COMBINATION LOW-PRESSURE 
AIR COMPRESSOR AND 
ENGINE DRIVE 

To provide the air necessary for operation of the 
small airborne Collins unit (Chapter 3), it was neces¬ 
sary to develop a lightweight small-capacity compres¬ 
sor to deliver 150 psi air and several extremely light¬ 
weight compressors for such service were visualized 
by contractors for the Army Air Forces, hut it was 
felt desirable to augment such work by a separate 
development in NDRC. The Clark Company under¬ 
took the development of a 30-cfm compressor built 
integrally with a gasoline engine drive. lle The unit 
was referred to as the Bobtail compressor and is so 
referred to in illustrations and performance curves. 

The final design was unique in that it consisted 
of a 4-cylinder, standard, air-cooled, horizontal-op¬ 
posed aircraft engine, modified to have two engine 
power cylinders and two single-acting compressor 
cylinders. Whereas the conventional air compressor 
has spring-actuated valves, this machine had mechan¬ 
ically operated poppet valves on the first-stage suc¬ 
tion. All other valves were spring actuated. 

Figure 18 shows the completed assembly, which 
consisted of the compressor, mounting frame, and 
Thermek spined-tubing intercooler. Figure 19 is a 
cross-section drawing showing pertinent details of 
the compressor cylinders. Table 5 gives the speci¬ 
fications of the unit. 

Figures 20, 21, and 22 show the results of per¬ 
formance tests on the compressor which was de¬ 
signed to compress 30 cfm at suction conditions with 
atmospheric suction and 150 psi discharge pressure. 





COMBINATION AIR COMPRESSOR AND ENGINE DRIVE 


69 



i 

Figure 18. Bobtail unit, 31.6 scfm, 150 psi. (2-stage 
air compressor and engine combined.) 


Table 5. Specifications Bobtail engine compressor unit. 


Type: Horizontal opposed 

integral engine 

Model: Bobtail 

Compressor data 

Rpm 

1,800 

Suction pressure 

0 psi 

Discharge pressure 

150 psi 

Capacity 

30 cfm at intake conditions 

Approximate BHP required 

15 

No. of Cylinders 

2 

Bore 

4)4 in. low stage (1) (mech. 

intake valves) 

4 l /\ in. high stage (1) 

Stroke 

3 )4 in. 

Engine data 

Rpm 

1,800 

No. of cylinders 

2 

Bore 

4 )4 in. 

Stroke 

3 )4 in. 

Approximate BHP delivered 

15.0 

Dimensions and weight 

Installation drawing 

104-10 

Overall length 

47 in. 

Overall width 

30 )4 >n. 

Overall height 

37 in. 

Approximate weight 

450 lb. 

Accessories supplied 

Air-cooled inter-, after-, and 
oil-cooler, oil pressure and 
temperature gauges, intake 
air filters, storage battery, 
ammeter, and mounting 
frame 


The machine had a number of defects which would 
render it useless for any commercial purpose. These 
are: high cost, relatively short life, inadequate oil 



control, crankcase vapor losses to the compressed 
air. The unit received thorough testing at Wright 
Field in connection with the Collins airborne unit. 

















































































































































































70 


AIR COMPRESSORS AND EXPANSION ENGINES 



Figure 20. Bobtail engine and compressor unit; capacity 
vs rpm at 150 psi discharge pressure. 



It was not accepted for further development for in¬ 
tegration with the Collins unit because it was con¬ 
sidered to he quite noisy and was heavier than com¬ 
pressors which the Air Forces felt sure would be 
developed before the end of the war. The program 


(C 



Figure 22. Bobtail unit; fuel consumption at 1,800 rpm. 

on the Bobtail unit was stopped early in 1943 after 
delivery of the one model. 

5 6 PORTABLE HIGH-PRESSURE 
COMPRESSORS 

Paralleling the development of the low-pressure 
air compressor, two designs were made up for 3,000- 
psi lightweight air compressors, especially for the 
Kellogg M-l and the Giauque unit (see Chapter 4). 
The first design used for the first two units, although 
satisfactory, was not considered completely success¬ 
ful; 35 ’ 36 and a second improved design was used in 
the building of the third and fourth machines of this 
type. 11 

The first two machines, designated as M-l com¬ 
pressors, are now obsolete, although the third and 
fourth, known as the Clark Model HO-6-4 high- 
pressure portable compressors, have proved to be of 
use to the Services especially for pressuring air for 
flame-throwers. At least 85 of these compressors 
have been supplied for this purpose. 

The obsolete design used the Franklin engine 
crankcase, while the final unit utilizes the more satis¬ 
factory Lycoming crankcase, which is also used in 
the low-pressure compressors previously described. 

This high-pressure compressor in its final form is 
undoubtedly the most successful compressor devel¬ 
oped in the NDRC program. Specifications for the 
unit are given in Table 6. Figure 23 shows the air 
compressor mounted on a base ready for attachment 
of an engine or motor drive. Figure 24 shows the 
compressor fully connected and suitable for operation 
in flame-thrower work. Figure 25 gives the cross- 
section of the first-stage cylinder. 

Compressor performance is illustrated graphically 
in Figures 26 and 27. Interstage pressure data at 
several speeds are also tabulated in Table 7. 







PORTABLE HIGH-PRESSURE COMPRESSORS 71 


Table 6. Specifications Clark Model HO-6-4, six cylinder, four stage, horizontal opposed compressor. 

Type: 6-cylinder, four 

-stage, horizontal opposed cross-head, oil lubricated, full force feed 

Model: HO-6-4 

Stages 

First 

Second 

No. of cylinders 

3 

1 

Bore 

5 in. 

4 in. 

Stroke 

3 % in. 

3 Y» in. 

Stages 

Third 

Fourth 

No. of cylinders 

1 

1 

Bore 

2 in. 

1 %e in. 

Shift 

3 in. 

3 Ys in. 

RPM 

900-1,800 


Suction pressure 

0 psi 


Discharge pressure 

3,000 psi 


Capacity 

At 900 rpm 

63.5 cfm 


At 1,800 rpm 

127.0 cfm 


BHP 

At 900 rpm 

Approx 40 

At 1,800 rpm 

Approx 100 

Dimensional data 



Installation drawing 

108-130 


Overall height 

64 Ys in. 


Overall length 

63 34 in- 


Overall width 

45 in. 

• Complete with cooler, etc. 

Weight without cooler and frame 1,000 lb. 


Weight complete with cooler and 


all accessories 

2,150 lb. J 


Accessories supplied 

Oil pressure and temperature gauges, oil filter, force feed lubricator 
and interstage manifolds 

Optional equipment 

Mounting frame, interstage piping, gauges, air-cooled inter- and after- 


cooler, knockout traps and over-pressure control 


Table 7. Interstage pressures Model H10-6-4 compressor. 



3,000 psi discharge 



1,900 rpm 


750 rpm 

1st stage suction 

0 

0 


1st stage discharge 

52 


49.4 

2nd stage suction 

49.7 

48 


2nd stage discharge 

180 


194 

3rd stage suction 

178 

193 


3rd stage discharge 

720 


665 

4th stage suction 

670 

630 


4th stage discharge 

3,000 


3,000 



2,000 psi discharge 



1,900 rpm 


850 rpm 

1st stage suction 

0 

0 


1st stage discharge 

47 


46.5 

2nd stage suction 

44 

45 


2nd stage discharge 

178 


183 

3rd stage suction 

176 

182 


3rd stage discharge 

645 


600 

4th stage suction 

600 

555 


4th stage discharge 

2,000 


2,000 


All pressures pounds per square inch gauge 











72 


AIR COMPRESSORS AND EXPANSION ENGINES 




Figure 23. Clark 3 7 /s- in. stroke 6-cylinder, 4-stage 
0.3000-psi compressor. 


Figure 24. Clark compressor and intercooler, 120 scfm, 
3,000 psi discharge. 


The horsepower data shown in the curves were 
calculated from electrical readings for power input 
to the direct-current drive motor. It is believed that 
the actual horsepower consumption is 92% of that 
shown on the plots. 


5 7 450-HORSEPOWER LOW-PRESSURE 
AND INTERMEDIATE-PRESSURE 
AIR COMPRESSORS 

In connection with the large-scale liquid oxygen 
pilot plants, M-5 and M-6 15 (Chapter 3), it was de¬ 
sirable to build compact compressors to supply them 
with air. For the M-5 plant a compressor was de¬ 
signed to supply 2,160 cfm from 0 psi to delivery at 
90 psi. For the M-6 unit where the operation was 
to be at 600 psi it was thought that a unit could be 
developed to supply 1,060 cfm at 0 psi for delivery 
at 612 psi. This latter machine was to have com¬ 
pressor cylinders which could be attached to the 
low-pressure compressor; thus either of the two de¬ 
sired pressures and capacities could be developed 
from the same basic design. The compressor that 
was built was a 6-cylinder, 12-in. stroke, 600-rpm 
unit which could mount either five 10-in. bore x 12-in. 
stroke, double-acting, low-stage cylinders and one 
10 x 12-in. double-acting, high-stage cylinder for the 
0 to 90-psi condition or 10, 10, and 5 x 12-in. first-, 
second-, and third-stage cylinders for the 0 to 612-psi 
condition. It was planned that all tests requiring the 
90-psi air would be completed and then the 612-psi 
cylinders would be mounted for the balance of the 
tests. 11 

The compressor unit was completed in the summer 
of 1943 and was shipped to the Central Engineering 
Laboratory at Philadelphia, before any tests were 
made on the 612-psi cylinders. The machine has not 
been run with these high-pressure cylinders although 
the cylinders are at hand. 

Figures 28 and 29 are pictures of the compressor 
installed in the laboratory at Philadelphia, directly 
connected to a Clark 10 x 12-in., 8-cylinder, vertical 
diesel supplied by the U.S. Navy. Table 8 gives the 
specifications for the compressor. Charts showing 
performance as checked during the brief tests at 
Olean, N.Y., are shown in Figures 30, 31, and 32. 
Other performance data can be obtained from the 
operating records of the M-5 unit 34 (see Chapter 3). 
















450-HORSEPOWER AIR COMPRESSOR 


73 



Figure 25. Cross-section of first-stage cylinder in final design 3^-in. stroke four stage compressor 








































































































































































74 


AIR COMPRESSORS AND EXPANSION ENGINES 





Figure 26. High-pressure compressor power capacity 
and speed data. 


Table 8. Specifications Clark 10 in. x 12 in. vertical, 
450-hp air compressor. 

Type: Vertical, 6-cylinder, double-acting air compressor 

arranged for direct connection to engine 
Model: C VC-12 

Compressor data 

Gas to be compressed 
Capacity 
Suction pressure 
Discharge pressure 
RPM 

BHP required (approx) 

No. of cylinders (compressor) 

Type 
Bore 
Stroke 

Arrangement 

Dimensions and weight 
Installation drawing 
Overall length 
Overall width 
Overall height 
Total weight 
Accessories supplied 


Air 

2,100 cfm at intake conditions 
0 psi 
90 psi 
600 
525 
6 

Double acting 
10 in. 

12 in. 

5 low stage 
1 high stage 

91465 

12 ft 4 in. 

3 ft 10 in. 

8 ft 3 ^4 in. 

25,000 lb 

Oil pump, oil pressure and 
temperature gauges, full 
force-feed lubrication and 
half flywheel coupling 



Q. - ----- -- 

< 500 1000 1500 2000 2500 3000 3500 


DISCHARGE PRESSURE IN PSI 

Figure 27. High-pressure compressor capacity perfor¬ 
mance data. 

5 8 EXPANSION ENGINES 

One of the necessary features for successful adap¬ 
tation of a low-pressure cycle for the liquefaction of 
air and its subsequent fractionation is a highly effi¬ 
cient expansion engine. S. C. Collins built and per¬ 
fected a small reciprocating expansion engine 24,25 
which offered great promise for use not only in the 
very small airborne oxygen plants but also for the 
portable 1,000 cfh producers. Further work was 
done to develop the original Collins expander in the 
small size necessary for the Collins unit and also the 
Clark Company developed several larger size recipro¬ 
cating expanders based essentially upon the Collins 
expander. 11 

5 9 COLLINS SMALL-SIZED 

RECIPROCATING EXPANDER 

The reciprocating expansion engine is a closely 
fitting piston and cylinder equipped with intake and 
exhaust valves much the same as a steam engine. 




















COLLINS RECIPROCATING EXPANDER 


75 



Figure 28. Installation view Clark two-stage vertical M-5 compressor at NDRC Philadelphia Laboratory. 


The general arrangement is illustrated in the sketch 
of Figure 33. The piston has a diameter of 2 in. and 
a stroke of 2 in., making a displacement of 6.28 eu in. 
The most suitable difference in diameter between 
piston and cylinder has been found to be 0.0008 to 
0.001 in. Experiment over a range of clearances 


from 0.0002 to 0.0015 in. have shown that if the fit 
is better than a half-thousandth of an inch there is a 
great danger of severe friction developing because of 
small particles of solid carbon dioxide or other solid 
impurities. If the fit is poorer than one-thousandth 
of an inch an excessive amount of air leaks by the 
























CAPACITY CFM AT INLET PRESSURE AND TEMPERATURE 


76 


AIR COMPRESSORS AND EXPANSION ENGINES 



Figure 29. Diesel engine and compressor. 




Figure 31. Six-cylinder vertical 12-in. stroke com¬ 
pressor—capacity at 90 psi. 



Figure 30. Six-cylinder vertical 12-in. stroke com¬ 
pressor—capacity at 600 rpm. 


Figure 32. Six-cylinder vertical 12-in. stroke com 
pressor—horsepower at 1,600 rpm. 
















COLLINS RECIPROCATING EXPANDER 


77 



piston and the efficiency of the engine is reduced cor¬ 
respondingly. 

The piston and cylinder are made from nitralloy 
steel and are hardened, ground and polished to resist 
wear (Figure 34). There is no lubrication other 
than the thin film of air. If the proper clearance is 
allowed there is never any trouble from seizure and 
the leakage of air is about 1%. No trouble has yet 
been encountered from rust, although it is conceivable 
that if the machine is allowed to stand idle for some 
months while wet, a mild seizure may result. No 
trace of wear has ever been detected on any piston or 
cylinder even after 2,000 hr of operation. 

During operation the piston and cylinder are at 
approximately the temperature of liquid air and must 
therefore he insulated in order to conserve refrigera- 



Figure34. Expander parts. 


tion. For this reason a thin-walled stainless steel 
cylinder and long piston rod and valve stems are 
used to isolate the expansion cylinder from the cross¬ 
head and crankcase, and at the same time to offer 
sturdy mechanical support. The piston rod is a x /\- 
in. diameter stainless steel rod fastened to the nitral¬ 
loy piston at the upper end and to the aluminum 
crosshead at the lower end (Figure 35). 


Figure 35. Expander parts. 

The rod is not fastened rigidly to the nitralloy pis¬ 
ton because of the possible lateral stress which it 
might exert due to slight misalignment. The cou¬ 
pling is similar to a ball-and-socket joint except that 
only a very slight deflection need be allowed for, and 
it is important to have no longitudinal play. A closely 
fitting stainless steel tube is used to house the piston 
rod, and a stuffing box at the end of this tube in the 
warm region serves to prevent leakage from the 
expansion cylinder. The tube must he closely fitting 






























































































78 


AIR COMPRESSORS AND EXPANSION ENGINES 


because the annulus between tube and rod forms 
part of the dead space in the expansion cylinder; and 
this must be kept to a minimum for high efficiency. 

The expander valves are actuated by cams located 
on the crankshaft on which rollers ride attached to 
rocker arms. The motion is transmitted from the 
rocker arms to the valves by thin stainless steel pull 
rods running through the crosshead, through stuffing 
boxes, and up through stainless steel housing tubes. 
Because of the total lack of lubrication the valves can¬ 
not be accurately guided, and must therefore have 
self-aligning features to enable them to sit squarely 
on their seats. Each valve is coupled to its pull-rod 
by a ball-and-socket type of union which is free to 
align itself. The valves are held against their seats by 
strong stainless steel springs, too strong to be over¬ 
come by the maximum pressure developed in the 
expansion cylinder, but not too strong to be opened by 
the pull-rod and cam mechanism. 

The valve chamber is an aluminum casting having 
a partition which separates it into two compartments. 
The exhaust valve is in one compartment and the 
intake in the other (Figure 35). Each compartment 
receives a bronze pipe fitting to which is soldered a 
copper tube carrying the intake and exhaust air. 
Thin annealed aluminum gaskets are used to secure 
a pressure-tight seal between the valve chamber and 
valve plate, also between the valve plate and ex¬ 
pander cylinder, and again between the cylinder head 
and cylinder. The cylinder head which bolts on top 
of the assembly is fitted with a %-in. pipe connec¬ 
tion to the exhaust surge chamber. This enables the 
region back of the nitralloy piston to breathe and 
also recovers any air leaking past the piston. 

The valve timing in the engine is as follows: the 
intake valve opens 5 degrees before bottom center 
and closes 51 degrees before top center; the exhaust 
valve opens 10 degrees before top center and closes 
10 degrees before bottom center. The valve lift is 

Vie in- 

The efficiency of the expander operating at liquid 
air temperature has not been appraised accurately 
because of the difficulties involved in estimating insu¬ 
lation heat leaks and various other factors with any 
accuracy. The most careful estimates indicate effi¬ 
ciencies of 80% or better. 37 

The crankcase assembly is fairly standard in de¬ 
sign. The crosshead, connecting rod and crankcase 
itself are machined from aluminum castings. The 
crank, wrist pin, rocker arms and crosshead cylinder 
liner are steel. One unique feature is the fact that 


the cams are an integral part of the crankshaft and the 
valve pull rods pass through holes in the reciprocating 
crosshead. 

Several attempts, with little success, were made to 
find a satisfactory substitute for the nitralloy piston 
and cylinder combination, not because of any malfunc¬ 
tion of the device, but simply because of the precision 
machining and grinding and expensive heat treatment 
required. 11 

Various materials were tried out as packings in 
the piston rod and valve rod stuffing boxes. Some 
of these were artificial rubber (several types), mul¬ 
tiple rings of thick hard leather, multiple rings of thin 
flexible leather, moldings of graphitized asbestos, 
and standard graphitized asbestos rope. The most 
durable combination was found to be graphitized 
asbestos (either molded or in rope form) confijied 
between leather follower rings. Oil-resistant neo¬ 
prene is satisfactory for the valve rod stuffing boxes 
where the amount of motion is small. 


510 CLARK-COLLINS EXPANSION 
ENGINES 

S ion Two-Cylinder 4 x 3%-in. Engine 

The small Collins expansion engine was a single¬ 
cylinder unit whose principle features were that pis¬ 
tons were without rings ; the piston rods were flexible 
and of small diameter; the valves were flat seat, non- 
guided; packing glands operated at room tempera¬ 
ture ; and stainless steel was used to cut heat leak. 11 
In laying out the design for a 2-cylinder machine for 
twice the capacity of a single-cylinder Collins unit, the 
same features were retained and in addition there was 
built into the machine a loading device to dissipate the 
mechanical work of expansion, and a crankshaft and 
valve gear. Figure 36 gives a cross-sectional view of 
the final unit as used in the production models. 
Figure 37 is a picture of the machine. Table 9 gives 
the specifications for the unit. Detailed informa¬ 
tion on the development of the expander is covered 
in various progress reports. 4 ’ 7 ’ 13 ’ 14 The performance 
of the expander can be illustrated by Figures 38 
through 41. These curves illustrate but a few of the 
characteristics and are given here to show those of 
prime interest. Figure 38 illustrates the motion as 
controlled by a steel cam. Figure 39 illustrates speed- 
efficiency relations for several discharge pressures, 
Figure 40 shows the speed flow relations at the same 



CLARK-COLLINS EXPANSION ENGINES 


79 




Figure 36. Cross-section of final Clark-Collins expander 




























































































































































































































































































































































































































































STANDARD CU FT PER HR AT 
60 F AT 1 ATM 


80 


AIR COMPRESSORS AND EXPANSION ENGINES 



Figure 37. Expansion engine, 290 lb air/hr, air-film 
lubricated, 86 psi to 6 psi. 



Table 9. Specifications Clark-Collins Model CCER-3 
two-cylinder expansion engine. 

Type: Collins vertical 2-cylinder 

crank-end expansion 

integral compressor 

Model: CCER-3 

Expansion end specifications: 

No. of cylinders 

2 

Bore 

4 in. 

Stroke 

3 Id in. 

Cylinder type 

Lap-fitted piston and cylinder 
ringless piston 

Compressor end specifications: 

No. of cylinders 

2 

Bore 

4.5 in. 

Stroke 

3 Id in. 

Cylinder type 

Conventional trunk-type piston, 1 
compression and 1 oil control ring 

Design operation conditions: 

Design inlet pressure 

100 psia 

Design exhaust press 

22 psia 

Design inlet temp 

-250 F 

Design exhaust temp 

-306 F 

Capacity 

290 lb per hr 

RPM - design 

300 

Material specifications: 

Main lower crankcase 

Welded steel 

Upper crankcase 

Welded stainless steel 

Lower cylinder bead 

Stainless steel plate 

Exp air manifold 

Bronze casting 

Exp cylinder 

Nitralloy H - nitrided - hone finish 

Exp pistons 

Nitralloy H - nitrided - hone finish 

Valves 

Stainless steel 

Valve springs 

Stainless steel 

Piston rods 

Stainless steel 

Valve pull rod 

Stainless steel 

Packing exp end 

Dry asbestos 

Air comp cyl 

Steel weldment 

Air comp piston 

Eronze casting - cast iron rings 

Dimensional data 

Installation drawing 

102-104 

Overall height 

57 Vic, in. 

Overall width 

17 in. 

Overall length 

24 i% 6 in. 

Weight, complete unit 

650 lb (including insulation) 

Accessories supplied 

Oil pump, gauge and special 
wrenches 


discharge pressures. Figure 41 illustrates the effect 
of speed and discharge pressure on the refrigeration 
obtainable. 

At least 50 production models of this expander 
have been built and they have been found to be very 
dependable, easily serviced and, in general, have met 
the requirements of the Services with regard to 
lightness in weight and compactness combined with 
high efficiency. In continuous use, expansion effi- 


Figure38. Reciprocating expander characteristics. 


















CLARK-COLLINS EXPANSION ENGINES 


81 



Figure 39. Reciprocating expander characteristics. 



z 

LkJ 

O 

CL 

UJ 

Q. 

I 

> 

O 

z 


Figure 40. Reciprocating expander characteristics. 


CO 



CRANK ANGLE IN DEGREES WHERE 0 IS 
BOTTOM DEAD CENTER NO. I CYLINDER 

Figure 41. Reciprocating expander characteristics. 


ciencies of a little more than 60%. are being realized. 
With ordinary maintenance several of these machines 
have run for over three thousand hours. 

510 .2 Two-Cylinder 3x2-in. Walking 

Beam Type Engine 

After the highly successful operation of the 2-cylin- 
der expansion engine just described, it was felt de¬ 
sirable to build an engine for capacity of 150 lb of 
air per hr or approximately one-half the capacity of 
the larger engine and to operate between pressures 
of 100 psia and 22 psia. 11 This expander was to fit 
the requirements of an intermediate capacity low- 
pressure oxygen unit described in Chapter 3 under 
the heading of Medium-Capacity Air Transportable 
Unit—the M-3. 15 

In order to obtain the most compact 2-cylinder 
unit, it was desirable to change the larger design 
from the straight line arrangement of the original 
Collins unit and a so-called walking beam mechanism 
was developed. When this motion was combined with 
a small gear-driven flywheel, a combination crank¬ 
shaft and camshaft, and a combination lubricating 
oil pump and loading 'brake utilizing the flywheel 
gearing, resulted in a 2-cylinder engine weighing 
less than 130 lb. Figure 42. a cross-sectional view of 
this machine, shows the ingenious arrangement 
which resulted in this lightweight unit. 

This type expansion engine, while utilizing sev¬ 
eral new mechanical modifications, did not dispense 
with the time-tried Collins features noted in the 
previous section. Comparison with the cross-sectional 
view in Figure 36 shows the similarity between the 
machines. 

One machine was built up with valve equipment 
arranged for 80% cut-off as against the original de¬ 
sign of 25%. The crankshaft was extended so that 
the work could be absorbed by means of a gear-driven 
motor generator rather than the lube oil pump; this 
to facilitate operation at constant speed as required 
by the Collins cycle. (See Chapter 3.) 

Reports from Philadelphia 27 and Cambridge tests 11 
indicate that the thermal efficiency was about 70% 
under normal operating conditions. Table 10 gives 
the specifications of the unit. 

No commercial use has been made of the walking 
beam expander. The M-3 oxygen producing unit 
does not fit Service needs and further development 
of the expander was not carried out. 











82 


AIR COMPRESSORS AND EXPANSION ENGINES 



Figure 42. Cross-section of Clark-Collins walking beam expander. 













































































































































































































































































































































































































































































CLARK-COLLINS EXPANSION ENGINES 83 


Table 10. Specifications Clark-Collins walking beam 
two-cylinder expansion engine. 

Table 11. Specifications Clark two-cylinder, vertical, 
high-pressure expansion engine. 

Type: Collins vertical 2-cylinder, crank-end expansion, 

Type: Vertical, 2-cylinder 

, head-end expansion, external 

walking beam, oil pump loading device. 

loading device. 


Model: WBEx-1 


Model: HLE-1 


Expansion end specifications 

Expansion end specifications 


No. of cylinders 

2 in. 

No. of cylinders 

2 single acting 

Bore 

3 in. 

Bore 

4 y 2 in. 

Stroke 

2 in. 

Stroke 

7 in. 

Cylinder type 

Lap-fitted ringless piston and 

Cylinder type 

Long plunger-tvpe piston—ring- 


cylinder 


less, in lap-fitted cylinder 

Material specifications 


Design operating conditions 


Main lower crankcase 

Cast aluminum 

Design inlet pressure 

600 psia 

Upper crankcase 

Welded stainless steel 

Design exhaust pressure 

74 psia 

Lower cylinder head 

Stainless steel plate 

Design inlet temp 

-130 F 

Exp air manifold 

Bronze casting 

Design exhaust temp 

-260 F 

Exp cylinder 

Nitralloy H - nitrided - hone finish 

Capacity 

3,383 lb per hr 

Exp pistons 

Nitralloy H - nitrided - hone finish 

RPM design 

300 

Valves 

Stainless steel 

Material specifications 


Valve springs 

Piston rod 

Stainless steel 

Stainless steel 

Main lower crankcase 

Welded steel 

Valve pull rod 

Stainless steel 

Upper crankcase 

Welded stainless steels (18-8) 

Packing exp. end. 

Dry asbestos 

Upper cylinder head 

Bronze casting 



Intake manifold 

Bronze casting 

Design operating conditions 

Exhaust manifold 

Bronze casting 

Design inlet pressure 

100 psia 

Expander cylinder 

18-8 stainless and nitralloy 

Design exhaust pressure 22 psia 


lower 

Design inlet temp 

-250 F 

Expander pistons 

18-8 stainless and cast iron 

Design exhaust temp 

-306 F 


lower 

Capacity lb/hr 

150 

Valves 

Invar steel 

Flywheel rpm 

900 

Valve stems 

Invar steel 

Cylinder strokes per 

300 

Dimensional data 


min per cyl 


Installation drawing 

109-37 

Dimensional data 


Overall height 

79 Vje in. 

Installation drawing 

110-01 

Overall width 

24 y 2 in. 

Overall height 

37 z /4 in. 

Overall length 

39 in. 

Overall width 

11 Ms in. 

Approximate weight 

1,200 lb 

Overall length 

15Ms in. 

Accessories supplied 

Oil pump, oil gauge, V belts,. 

Overall weight 

125 lb 


“Hydrotarder” loading brake, 

Accessories supplied 

Oil piping and oil gauge 


and water cooler 


510 - 3 Two-Cylinder 4^4x7-in. 

High-Pressure Expansion Engine 

For the M-6 liquid oxygen pilot (see Chapter 3), 
a high-pressure expansion engine was developed. 11 
In most particulars the same general principles and 
construction used for the previously described re¬ 
ciprocating expanders were used. Specifications for 
the unit are shown in Table 11. A cross-sectional 
drawing is shown in Figure 43. 

The design consists of a conventional crankshaft, 
connecting rod, and crosshead but the upper or ex¬ 
pansion end is rather unusual. The expansion end 
crankcase is fabricated from 18-8 stainless steel as in 
the other expansion engines but the expansion takes 
place on the head end rather than on the crank end 
of the cylinders as in the other expansion engines. 
The valves are mounted in the head and a long pis¬ 


ton operating in an extremely long cylinder without 
piston rings enables this machine to operate effi¬ 
ciently and with an extremely low amount of air and 
heat leakage. The valves and valve guides are un¬ 
usual in that no packing is utilized. A seal is main¬ 
tained merely by close tolerances. 

Whereas the other units have had a built-in loading 
brake, the Clark high-level expansion engine is 
V-belt connected to a Parkersburg Rig & Reel Co. 
“Hydrotarder,” a novel form of hydraulic dyna¬ 
mometer. This arrangement gives the same type of 
variable speed operation as is found on the smaller 
Clark-Collins’ expansion engine. 

Tests of the high-level expander operating in the 
M-6 plant, made at Stamford and totaling about 300 
hr indicate that the engine is capable of expanding air 
with a heat drop efficiency of 85% under the condi¬ 
tions of operation required. 15 ’ 38 Mechanical operation 








84 


AIR COMPRESSORS AND EXPANSION ENGINES 



Figure 43. Cross-section of Clark high-pressure expander. 


has been entirely satisfactory at speeds up to 275 
rpm but it is not considered practical to operate at 
speeds over 300 rpm. Owing to this speed limitation 
it has been necessary to increase the cut-off to about 


32% in order to get sufficient throughput to run the 
M-6 unit at designed conditions and at this increased 
cut-off the efficiency has dropped to about 80% be¬ 
cause of incomplete expansion. 





























































































































































































































































































































































































































TURBINE-TYPE EXPANSION ENGINES 


85 


511 TURBINE-TYPE EXPANSION 
ENGINES 

5,111 Large Turbo-Expander, 

Capacity 7,050 Lb of Air Per Hr 

One of the important mechanisms required to 
achieve compact design for low-pressure air lique¬ 
faction is an efficient expansion engine. Kapitza in 
Russia was reported to have had success in the opera¬ 
tion of a turbine-type expander, and it was rumored 
that the Linde Company in Germany had used such 
an expander in connection with Linde-Frankl oxygen 
units. No data were available in this country on the 
design or performance of such expanders and one 
of the first projects laid out by this section was that 
of producing a high-capacity turbo-expander. The 
unit was projected as a part of the M-5 unit (see 
Chapter 3), and indeed it was necessary to set up the 
M-5 plant before the turbo-expander could be tested 
thoroughly under the required pressure and low- 
temperature conditions. 

The quantity of air necessary to expand in order 
to obtain a given amount of refrigeration is inversely 
proportional to the efficiency of the expander; thus 
high efficiency is essential to the success of the appli¬ 
cation. The quantities involved, especially in this 
particular job, would be large for a reciprocating 
machine but are quite small as turbine sizes go. Con¬ 
ventional turbine seals were too imperfect and a 
special shaft seal had to be worked out; because of 
the low temperature a selection of materials was 
limited; cold losses to the surrounding atmosphere 
constituted another difficulty; and the high speed at 
which the machine needed to operate introduced a 
critical shaft problem and a bearing problem. Because 
of their inter-relation, the problems had to be studied 
more or less simultaneously, but they are presented 
separately below. 

It was concluded at the outset that the turbine 
would have to be of simple design and that it would 
have to be either a single-stage axial impulse turbine 
or a radial turbine. A preliminary design of the axial 
turbine revealed wheel construction difficulties, a 
difficult critical shaft problem because of a heavy tur¬ 
bine wheel, probable low nozzle efficiency, and an 
insufficiently high overall efficiency estimated at 
71 19 > 2 °> 22 > 33 > 34 

An investigation of the radial turbine showed that 
the turbine wheel would be lighter and easier to con¬ 
struct and should have substantially higher efficiency 


if properly proportioned. Accurate and complete 
data on the impulse-type turbine were available so 
that its characteristics were rather easily estimated, 
but very little was known about the radial turbine, 
and almost every phase of it had to be rather carefully 
studied. 

Final Design 

The final arrangement of the turbine, 26,34 shown in 
Figure 44 consisted of a in. OD aluminum turbine 
wheel mounted on a 1-in. shaft in cantilever fashion 
3 in. from the nearest bearing. The shaft was sup¬ 
ported in two bearings. The one nearest the turbine 
was a sleeve bearing and it also constituted the shaft 
seal. The bearing farthest from the turbine wheel 
carried the thrust load and it was a ball bearing. 
This bearing assembly was supported upon the tur¬ 
bine case by means of a thin walled stainless steel 
sleeve of rather large diameter. Thus mechanical 
strength was attained without undue cold loss from 
the cold turbine case. The shaft between the warm 
bearing and the cold turbine wheel, being 3 in. long 
and of stainless steel, resulted in a negligible heat 
leak. 

The case was a stainless steel casting in two parts. 
The nozzles were built into a separate assembly 
which fit in between these two parts. The turbine 
was mounted by the case by means of three 3-in. 
diameter stainless steel tubes 6 in. long so arranged 
that temperature changes would not disturb the shaft 
alignment between the turbine and the loading device 
to which it was coupled. The length of these tubes 
was sufficient to extend through the insulation and 
to prevent any but negligible loss by conduction. 
Measurement of shaft mis-alignment as a result of 
various loads applied to the suction and discharge 
flanges, showed that this means of support was ade¬ 
quate, if suitable expansion joints in the connections 
were used. 

Operation. The operation of the turbine is as fol¬ 
lows. The cold high-pressure air (103 psia and 
—242 F) enters the volute chamber and passes 
through the peripheral nozzles by which the air is 
accelerated in a tangential direction to a little over 
600 ft per sec and in a radial direction to about 
100 ft per sec. At this point, it enters the periphery 
of the wheel. The wheel has radial blades and the 
periphery of the wheel is traveling at a little over 600 
ft per sec so there is no shock at this point. The gas 
flows inward between the radial blades and is uni¬ 
formly decelerated to about 300 ft per sec before it 



86 


AIR COMPRESSORS AND EXPANSION ENGINES 



reaches the wheel discharge at 20 psia. At the wheel 
discharge the blades are so curved as to form an¬ 
other set of nozzles which are directed backward with 
relation to the direction of wheel rotation, and the 
gas is discharged from these nozzles at a relative 
velocity of about 300 ft per sec. Thus the air is dis¬ 
charged from the wheel with no rotational velocity. 
It works out that about half the energy in the air is 
spent in the primary nozzles, about 35% is spent in 
opposing the centrifugal force field within the wheel 
and about 15% in the wheel discharge nozzles. The 
efficiencies at which these various transformations 


of energy were accomplished were either measured 
in special apparatus or estimated, and on the basis 
of these figures the turbine elements were so pro¬ 
portioned as to minimize the total losses. 34 

During operation, the prevailing pressure around 
the shaft is 25 or 30 psi. The leak rate of conventional 
seals would permit a prohibitive loss of cold air, so 
the inboard bearing was made a sleeve bearing and 
was used at the seal. Oil was delivered to this bear¬ 
ing under sufficient pressure that a portion of it 
flowed each way axially along the bearing clearance. 
The portion which flowed inwardly flowed into a 








































































































































































TURBINE-TYPE EXPANSION ENGINES 


87 


chamber which communicated directly with the pres¬ 
sure around the shaft. An adequate system of baf¬ 
fles was arranged around the shaft so that the oil 
did not enter the air stream. The oil drained into a 
chamber whence it was automatically trapped to the 
atmospheric storage reservoir. The portion of the 
oil which flowed outward passed over a weir and its 
level was thus maintained at such a point as was 
necessary to lubricate the ball bearing properly. 

Loading Device 

The turbine was direct-coupled by means of a 
special Thomas flexible coupling to a reducing gear 
wherein the speed was reduced from 22.000 rpm to 
3,600 rpm. The 3.600 rpm shaft was direct-coupled 
by means of another Thomas coupling to an Elliott 
35 kw, 110 v, d-c generator. The power generated by 
the turbine was thus converted to electrical energy 
and spent in a suitable Westinghouse resistor bank. 

Numerous other loading devices were considered, 
but this seemed to be the cheapest as well as the most 
useful one that was proposed, especially in view of the 
development work required for the others. 

An electrical tachometer was direct-coupled to the 
generator shaft. The voltage from this tachometer 
actuated an indicating and recording instrument and 
also a special relay which would trip the solenoid 


valve in the compressed air inlet to the turbine. It 
was so arranged that the valve would be automati¬ 
cally tripped shut if the speed should become ex¬ 
cessive, for an obvious reason, and also to trip the 
valve if the speed should become too low. This latter 
provision was an attempt to safeguard against the 
condition of a failure of the coupling or gear, since 
in the event of such a failure the generator would 
promptly slow down. 

Experimental Expander 

In order to prove the most questionable points in 
this proposed design as described, an experimental 
turbine was planned for operation on room tempera¬ 
ture dry air. The doubtful points which were to be 
explored were: 

1. The operability of the shaft assembly. 

2. The oil seal. 

3. The nozzle efficiency. 

4. The wheel structure and mechanical strength. 

5. The general assembly. 

6. Efficiency. 

Attainment of consistent efficiency results between 
the warm air and the cold air condition was not sub¬ 
ject to serious doubt. 

With these factors in mind, an experimental tur¬ 
bine as shown in Figure 45 was built. The turbine 



Figure 45. M-5 unit—parts of large turbine expander. 





88 


AIR COMPRESSORS AND EXPANSION ENGINES 


was designed to operate at an expansion ratio which 
required the same wheel tip speed as would be re¬ 
quired for the cold air. No essential difference in the 
nozzle design between the warm and cold air was 
necessary, and the warm air nozzles were made iden¬ 
tical in design and dimensions to those planned for 
the final cold air unit. Different materials, however, 
were used. The turbine case, seals, shaft, bearings, 
and turbine supports were also made identical with 
corresponding parts planned for the final unit. The 
turbine wheel was of the same diameter and had the 
same blade and peripheral width as the wheel in the 
final proposed unit. The wheel passages and wheel 
discharge area had to be different in order to cor¬ 
respond with the volume variation under this some¬ 
what different condition and this was accommodated 
by alteration of the wheel profile. The air supply, 
on which the turbine operated, was dried by passing 
it through a large anhydrous calcium chloride bed, 
and its pressure controlled by a Fisher regulator. The 
turbine case was insulated and the efficiency was 
measured by temperature difference between the in¬ 
let and discharge. In order to minimize the error 
due to cold loss, the discharge was run at an elevated 
pressure so as to increase the throughput of air. The 
loading device consisted of two 5 kw d-c generators 
belted to the turbine wheel. 22 

The turbine efficiency was measured at various 
pressure ratios and at various turbine speeds. The 
results of a typical set of these data are shown in 
Figure 46, wherein efficiency is plotted against the 
ratio of kinetic energy at wheel tip speed velocity to 
total expansion energy of the air. These tests proved 
the points enumerated above, and in the final unit 
the parts were duplicated in suitable anti-embrittle¬ 
ment material. The wheel profile was necessarily 
changed to correspond with the volume changes that 
would occur under the low temperature conditions. 
It was not expected that any perceptible difference 
would be found. 

During the testing of the warm air unit, it was 
requested that a study be made to determine how 
small these turbines could be built. The doubtful 
point in this study was the nozzle efficiency, so a 
special nozzle ring with three times as many nozzles 
one-third as large was made to fit into the warm air 
turbine. The minimum throat dimension in this new 
set of nozzles was about y iG in. The efficiency of 
these nozzles was lower than that for the larger ones 
which themselves were quite small, but the difference 


was barely measurable and it indicated that an effi¬ 
cient small turbine could be built. 

Performance of Final Unit 

After a few initial minor difficulties were over¬ 
come, the performance of the machine has been com¬ 
pletely satisfactory, and a total operating time of over 
1,100 hr has been accumulated. 34 Low-temperature 



O O.l 0.2 0.3 0.4 0.5 0.6 


Ah 

AH 

Figure 46. Turbo expander efficiency. 

tests have produced the results shown in Figure 47, 
in which expansion efficiency at optimum speed is 
plotted against expansion energy per pound in the 
cold air. 26 - 27 ’ 30 ’ 31 ’ 32,33 This confirmed the expectation 
of little or no difference between warm and cold per¬ 
formance. It was not expected, however, that the 
curve would be as straight and flat as it is, and some 
inefficiency in the wheel discharge is indicated. Esti¬ 
mated operating characteristics of the machine are 
shown in Figure 48. 

Mechanically the turbine has operated very well. 
There has been no noticeable wear except on the 
pinion of the reducing gears, which quickly became 





TURBINE-TYPE EXPANSION ENGINES 


89 


pitted at the pitch line but which is still operating 
satisfactorily. The ball hearings have remained in 
perfect condition; the shaft hall bearing carries a 
thrust load of about 300 lb at 22,000 rpm, and one of 
two ball bearings supporting the pinion gear is simi¬ 
larly loaded. 


too 

1 

1 1 1 1 1 1 1-1-1-1-1—1-1-1-1— 

o X # 

80 


6 °o o 0 A ° A °A *#‘y — &_ 



- 

60 


- 



- 

40 


NOMINAL INLET TEMPERATURES 


“ 

X 70 F 

20 


A -60F 
• -140 F 


_ 

O - 245 F 

O 

_J_ 

-1_1_1_1_1_1_1_1_1_1_1 1 1 1 l 


5 IO 15 20 

IDEAL ENTHALPY DROP -BTU PER POUND 

Figure 47. Expander efficiency at optimum speed. 



Figure 48. Operating characteristics of large turbo ex¬ 
pander. 


Initial difficulties include (1) overheating of the 
shaft hall bearing, (2) excessive oil frothing, (3) ex¬ 
ternal oil leakage from the shaft, (4) severe nozzle 
erosion, and (5) low air capacity. The bearing over¬ 
heating was caused by churning in a pool of oil, and 
the condition was corrected by eliminating an oil 
pocket. The oil circulating system was revised to 
handle the oil froth, hut the frothing condition has 
not been encountered in normal operation with cold 
air; the earlier condition probably resulted from con¬ 
tamination of the oil with water during preliminary 
testing with warm, undried air. A minor revision 
practically eliminated the oil leakage. The nozzle 
erosion was eliminated by substituting nitrided stain¬ 
less steel for the original mild steel, and enlarging 
the nozzles corrected the low capacity. In addition, 
there was one unexplained sleeve hearing failure, and 
a second failure caused by a breakdown in the auxil¬ 
iary lubricating oil system. 26 ’ 27 


It should be possible to build such a turbine to 
operate at an efficiency of 87 or 88% ; thus, losses 
amounting to 5% in this machine could probably be 
eliminated if a considerable effort is made to do it. 
The major portion of this preventable loss is proba¬ 
bly in the wheel and in the wheel discharge. The 
wheel passages are not nearly as smooth as they could 
he made as the result of foundry experience in making 
these wheels. 

A reapplication of the methods used in selecting 
the wheel speed and wheel dimensions if based on 
more accurate data on the individual losses within the 
turbine would probably indicate a somewhat different 
size of wheel and thus result in a slight increase in 
efficiency. 

As a result of this study it appears as though the 
turbine can he built in any size larger than about 250 
lb of air per hr, and that in any hut the smallest 
sizes the expansion ratio could he considerably larger 
than has been used in this unit. 

5 112 Small Turbo-Expander Capacity 290 
Pounds of Air per Hour 

A turbo-expander to handle 290 lb of air per hr 
would meet the refrigeration requirements of a 1,000 
cfh mobile gaseous oxygen producer. 34 As finally 
built, such an expander including its loading mecha¬ 
nism was but a fraction of the weight and size of the 
reciprocating expander for the same duty (compare 
Figures 37 and 49). Perfection of this expander 
together with successful development of a high-speed 
rotary compressor (Lysholm compressor, Section 
5.4) were enticing goals which would result in ex¬ 
treme compactness and lightness in weight for oxy¬ 
gen production equipment. 

Because of the considerable interest in portable 
oxygen plants, it was desirable to ascertain the lower 
size limitations of this type turbo-expander. Small 
machines are generally less efficient than large ones, 
but many of the power losses originate in compara¬ 
tive inaccuracies and comparative roughnesses of 
passages. This type expander is quite simple in de¬ 
sign so that additional care and attention to these 
factors would not be unreasonable. It was hoped 
that a rather small unit might have acceptable effi¬ 
ciency. 

It had been found possible to build efficient nozzles 
in small sizes so the possible source of greatest energy 
loss was already known to be insignificant. The 









90 


AIR COMPRESSORS AND EXPANSION ENGINES 


design experience from the large expander was extra¬ 
polated into the small size and this indicated a rota¬ 
tional speed of about 80,000 rpm, an impractical 
speed. A two-stage expander was then studied where 
half of the enthalpy drop took place in each wheel. 
This gave a machine which needed to rotate at just 
under 50,000 rpm, which speed was considered pos¬ 
sible. A shaft seal for this speed was not considered 
to be practical, but it was presumed that a worm 
gear could operate under pressure to reduce the 
rotating speed to 3,600 rpm, and then a seal could be 
put on the 3,600 rpm shaft. 



Figure 49. Two-stage turbine expander with electric 
generator. 


In spite of the apparent feasibility of the gear, it 
proved to be a difficult design problem and was aban¬ 
doned in favor of a generator-type loading device, 
which had the following salient advantages: 

1. The generator bearings acted also as the turbine 
bearings. 

2. It was possible to build in a self-contained lubri¬ 
cation system. 

3. The load could be varied over wide ranges and 


an estimate of its value read from electrical instru¬ 
ments. 

4. The frequency of the generated current was a 
direct measure of the speed. 

5. The size was reasonable. 

The first model, which never proved entirely satis¬ 
factory, consisted of a rotaing element mounted in 
two high-speed ball bearings between which was 
located a lj4-in. diameter Alnico magnetic rotor, 
and two turbine wheels mounted on the end of the 
rotating shaft and overhanging the bearing about 
2 in. 28,29 This 2 in. of shaft was sufficient to reduce 
the cold loss to a tolerable amount. The generator 
stack was 3 in. long and had a two-pole three-phase 
winding. The stator case was attached to the tur¬ 
bine case by means of a thin-walled cylinder. This 
thin-walled cylinder joined the warm generator and 
the cold turbine and cold losses through it likewise 
were small. The whole unit was supported by at¬ 
tachments to the turbine case. The arrangement may 
be seen in the accompanying Figure 50, and a photo¬ 
graph is shown in Figure 51. 

Although the critical speed of the shaft was esti¬ 
mated on the basis of actual flexibility measurements 
to be above 64,000 rpm it would not run satisfactorily 
above 40,000 rpm and was at times rough at that 
speed. 29 This was considered to be due to the dual 
purpose served by the bearings, so the unit was re¬ 
vised to include a third bearing. Two of the bearings 
then supported the heavy rotor magnet and the third 
bearing gave guidance to the turbine shaft. This 
arrangement eliminated the shaft run-out difficulty. 
It has a calculated critical shaft speed in excess of 
100,000 rpm. 

Lubrication 

Oil was transported to all three bearings by means 
of a circulating stream of air. The lower end of the 
shaft was drilled in such a way that it picked up oil 
from the reservoir into which it extended and atom¬ 
ized it. The resulting oil fog was circulated through 
all bearings by a blower effect attained by slots cut 
in suitable disks mounted adjacent to the bearings. 
Changes in pressure in the turbine caused pulsations 
into the closed space within the generator and except 
for a special provision would cause a breathing of this 
oil fog into the turbine. This was prevented by lead¬ 
ing a stream of clean air from the point of highest 
pressure within the generator to a lantern ring on the 
overhanging turbine shaft so that clean air flowed 
from that point into the generator at all times, and 













TURBINE-TYPE EXPANSION ENGINES 


91 






SECTION C-C 





p= 
< == 

1 


/A — 


yy 

yy, 



SECTION B-B SECTION A-A 

Figure SO. Assembly drawing of two-stage expander. 


any breathing was from this supply of clean air. The A survey of the pressure existing at the various 
air was made clean by bringing it through a suitable critical points during operation demonstrated the 
wire cloth cartridge outside the generator casing, workability of this lubricating system. 


































































































































































































































































































































































92 


AIR COMPRESSORS AND EXPANSION ENGINES 


Loading Device 

The loading device consisted of a 200 v, 2 kw gen¬ 
erator which used a permanent two-pole magnet 
rotor. The speed limited the diameter and the neces¬ 
sary generator stack length was estimated at 2 in., 
but for safety in the first unit, it was made 3 in. long. 



Figure 51. Two-stage turbo expander with speed indi¬ 
cator. 


The magnet was found capable of withstanding con¬ 
siderable electrical abuse and was not so critical as 
was anticipated at first, and in fact is not critical 
at all. 

The chief difficulty in the generator was the high 
inductance within the coils, which limited the pos¬ 
sible load current. This was known to be a diffi¬ 
culty and it was planned to use an outside capaci¬ 
tance in combination with the resistance load to 
raise the load current. It turned out to be an easy 
matter to produce the required load by means of a 
condenser of reasonable size. 

Other types of loading devices considered were 
the aforementioned worm gear, a direct-connected 
fan, and an enclosed fan. The gear, as pointed out 
before, proved to he less attractive when carefully 
examined. The direct-connected fan would require 


a shaft seal operating against a high pressure dif¬ 
ference and at above twice the permissible running 
speed. The enclosed fan was workable except that 
it would not have a wide load range and would not 
give a measure of speed. 

Speed Indicator 

A special speed indicator was built which was 
actuated by the frequency of the generator current. 
It consisted of a means for discharging a condenser 
through an ammeter once each cycle, the condenser 
being charged each time to a constant voltage. It 
proved to be a very satisfactory speed indicator 
except that separate lOOv power was required for 
its operation. 

Performance 

On warm air at full rated pressure, the unit gave 
better than 50% efficiency, which is substantially 
better than that of the large single-stage unit under 
identical conditions. This means that its starting-up 
characteristics will be better than the large one, and 
this is due to the two-stage arrangement. It runs 
very smoothly and is easy to control. 34 

Fouling of the wheels and nozzles with oil has not 
yet been eliminated completely, and this has pre¬ 
vented testing the turbine under cold conditions. 

The unit weighs about 25 lb and could he made 
to weigh half this amount, if necessary. It is esti¬ 
mated that the control box and load resistors occupy 
about 1 cu ft. The unit is considered to be easy to 
manufacture, to have satisfactory life, to he mechani¬ 
cally sound, and easy to operate. Its shortcomings 
will probably originate in the difficulty of maintaining 
its capacity because of the small nozzle passages and 
other passages being continually partially plugged by 
an accumulation of ice. 

The unit requires considerable testing to determine 
bearing life, coil insulation life, and lubricant life. 
The coil insulation is subjected to rather high tem¬ 
peratures under considerable air pressure in the 
presence of oil. 

Development work on this expander will continue 
after completion of NDRC work under Navy Con¬ 
tract NObs 2477 and operating results will be availa¬ 
ble from reports of the University of Pennsylvania 
Thermodynamics Research Laboratory operating 
under that contract. 







Chapter 6 

OXYGEN COMPRESSORS AND LIQUID OXYGEN PUMPS 

By /. H. Rushton 


61 COMPRESSION OF OXYGEN 

O ne of the most important uses for oxygen to be 
produced by mobile equipment was for aviator 
breathing. It is not only necessary to have high- 
purity oxygen for aviation breathing purposes but 
it is absolutely essential to have the oxygen dry (speci¬ 
fications : dew point, —70 F). Low temperatures are 
encountered in high altitude work and it is imperative 
that the moisture content of aviation oxygen have 
a dew point so low that there would be no chance for 
deposition of water in the supply lines from oxygen 
cylinders to the aviator’s mask. The conventional 
oxygen compressor is used to compress oxygen from 
approximately atmospheric pressure to 2.200 psi. 
This pressure of 2.200 psi is the pressure normally 
maintained in the oxygen cylinders used throughout 
industry in the United States. These compressors 
are ordinarily lubricated by water or dilute solutions 
of glycerin in water. Thus the compressed oxygen 
contains a considerable amount of water vapor after 
being compressed in a cylinder lubricated in this 
fashion so that, for breathing oxygen, it is necessary 
to install some drying device on the compressor 
whereby the dew point of the compressed oxygen 
can be brought down to acceptable limits. 

Perfectly dry oxygen gas can also be charged to 
high-pressure cylinders by starting with liquid oxy¬ 
gen placed in a high-pressure vaporizer where the 
oxygen is caused to evaporate, usually by the addi¬ 
tion of heat from an external source, and pressure is 
allowed to build up in the vaporizer which can then 
be attached to oxygen cylinders for charging. The 
oxygen will then fill the cylinder, and pressures up 
to 2,200 psi can easily be obtained. This is a well- 
known commercial process and is used in this country 
and also in Great Britain where pressures up to 3,000 
psi are normally used. By this vaporization process 
it is possible to obtain perfectly dry oxygen gas and 
thus the necessity for operating a water-lubricated 
compressor, as well as the subsequent drying equip¬ 
ment, is eliminated. 

Because of a number of circumstances and tactical 
uses for gaseous oxygen it was desired that NDRC 
develop gaseous oxygen producers for the Army Air 


Forces and Engineer Board. Of secondary impor¬ 
tance was the development of mobile liquid oxygen 
producing equipment. The next problem was whether 
a successful nonlubricated oxygen compressor could 
be developed, thus eliminating the considerable equip¬ 
ment and weight of a plant which would call for the 
conventional type of oxygen compression with a sub¬ 
sequent drying process. 2 

Since the section was interested also in the develop¬ 
ment of liquid oxygen producers both of small and 
large capacity, several vaporizers and liquid oxygen 
pumps 3 ’ 4 ’ 5,6 ’ 7,8 were developed for use with such 
plants. 

Another method available for direct production of 
dry gaseous oxygen without the use of a gaseous 
compressor was the use of a liquid oxygen pump. 
A liquid oxygen pump is used to compress liquid 
oxygen within the cold box of a producing unit, and 
the compressed liquid is then returned through the 
heat exchange system of the unit so that it extracts 
heat from the incoming process air and is discharged 
at the desired high pressure (2,200 psi), in the gase¬ 
ous form, at a temperature only a few degrees below 
that of the incoming air. Such a pump will therefore 
allow the production of dry gaseous oxygen and the 
recovery of enthalpy in changing from liquid oxygen 
to gaseous oxygen at room temperature. This recov¬ 
ery of heat cannot be achieved in the usual liquid 
vaporization process described above. There is a 
limitation to the use of a liquid oxygen pump from 
the process standpoint; it can be applied with good 
thermodynamic efficiency only to processes in which 
the air feed is at 250 to 300 psi or higher. Thus, the 
liquid oxygen pump has not been applied to the low- 
pressure process (that is, 100 psi and 150 psi) but 
has been applied with considerable success to process 
operating at above 600 psi. 

6.2 two-stage nonlubricated 

OXYGEN COMPRESSOR 

The first attempt to build a dry oxygen compressor 
was in connection with a regenerative chemical unit 
(Chapter 11). Oxygen produced by this unit would 
be available at or a little below atmospheric pressure 


93 


94 


OXYGEN COMPRESSORS AND LIQUID OXYGEN PUMPS 


but was to be delivered to low-pressure gas storage 
tanks at 150 psi. The first development was a four- 
stage oxygen compressor which was intended to be 
water lubricated. 2 The simplest method for design of 
the low-pressure two-stage dry oxygen compressor 
was to modify the four-stage water lubricated com¬ 
pressor by using the main crankcase, the upper crank¬ 
case, and the first and second stage cylinders. Speci¬ 
fications for the compressor are given in Table 1. 


Table 1. Specifications Clark two-cylinder, two-stage 
0-150 psi Dri-oxygen compressor. 


Type: Vertical, two-cylinder, two-stage, nonlubricated, 

water-cooled, single acting. 

Model: DVO-2-2 

Compressor data 

Suction pressure 

0 psi 

Discharge pressure 

150 psi 

Maximum inlet temp 

120 F 

Capacity 

16.6 cfm at intake conditions 

Approximate blip re- 

quired 

7.0 

RPM 

700 to 860 

No. of cylinders 

2 

Bore 

5 in. and 3.5 in. 

Stroke 

3.5 in. 

Design features 

Cylinder 

Highly polished chromium- 
plated bronze 

Piston rings 

Segmental graphitar No. 2 
carbon 

Dimensions 

Installation drawing 

103-50 

Overall length 

26 in. 

Overall width 

20 in. 

Overall height 

35 Vz in. 

Approximate weight 

400 lb. 

Accessories supplied 

Oil pump and oil pressure gauge, 
water piping and flywheel 
grooved for V-belt drive 


Special pistons replaced those of the tandem design. 
Except for the absence of the third and fourth stages 
and the addition of new cylinder heads, the new 
machine was identical with the original. Figure 1 
is an early view of the first two-stage unit, and Figure 
2 is a cross-sectional drawing of the two-stage ma¬ 
chine. 

Data on the performance of the unit were collected 
under varied operating conditions during a total of 
75 hr of actual test work. The data and mechanical 
operation were carefully checked as the experience 
gained was expected to be of considerable value in 
connection with the work on the four-stage machine. 
Figures 3, 4, 5, and 6 are illustrative of the perform¬ 
ance of the two-stage compressor. 


All tests utilized air as the test medium, since at 
that time a supply of oxygen was not at hand. It 
was thought that this would not introduce a serious 
error in the work because of the similarity of the 
thermodynamic properties of air and oxygen. 



Figure 1. Vertical two-stage dri-oxygen compressor. 

The test runs brought to light a number of minor 
difficulties and troubles which were corrected. No 
serious mechanical difficulties were experienced and 
the carbon rings showed no evidence of undue wear. 

The design shown in Figure 2 is simple and con¬ 
ventional. The only innovation was the segmental 
carbon rings operating on a heavy, bright polished, 
chromium-plated cylinder liner. Figure 7 shows a 
closeup of a set of carbon rings typical of those used 
on the oxygen compressor on the first and second 
stages. 

Of this type, only two machines were built. The 
first was incorporated with the Salcomine oxygen 
generating plant (Chapter 11) aboard the USS 














v/72. 


TWO-STAGE NONLUBRICATED OXYGEN COMPRESSOR 


95 



Figure 2. Cross-section of two-stage 3j4-inch stroke dry oxygen compressor 














































































































































































































































































































































































































































96 


OXYGEN COMPRESSORS AND LIQUID OXYGEN PUMPS 



Figure 3. Two-stage dry oxygen compressor pumping 
air at 700 rpm, 150 psi discharge typical low-stage com¬ 
pressor card. 



Ul 

5 

5 

<E 


z 


<a 


o 

Ul 

fc 

3 


2 

U. 

o 

£ 

o 

< 

a 

< 

o 


RPM 



Figure 6. Two-stage dry oxygen compressor; capacity 
vs discharge pressure and rpm (pumping air). 


Prairie, a Navy destroyer tender; the second was 
delivered to the Central Engineering Laboratory in 
Philadelphia. 


Figure 4. Two-stage dry oxygen compressor pumping- 
air at 700 rpm, 150 psi discharge typical high-stage com¬ 
pressor card. 



DISCHARGE PRESSURE PSI 


Figure 5. Two-stage dry oxygen compressor; indicated 
compressor horsepower vs discharge pressure, atmos¬ 
pheric intake (pumping air). 


6 3 FOUR-STAGE NONLUBRICATED 
OXYGEN COMPRESSOR 

In the early work on development of oxygen com¬ 
pressors it was felt that there would be little chance 
of success for building a nonlubricated oxygen com¬ 
pressor for delivery at 2,000 to 2,200 psi. 2 Accord¬ 
ingly, the first oxygen compressor was designed to 
be water-lubricated using micarta rings with polished 
chromium-plated brass or bronze liners. A machine 
for water lubrication was built and underwent many 
hours of test work. Meanwhile the two-stage low- 
pressure nonlubricated compressor described in the 
previous section was built. The test runs were so 
satisfactory that it was believed that a successful non¬ 
lubricated four-stage high-pressure compressor could 
be designed. During the development of the oxygen 
compressor a considerable effort was put forth to 
convert the water lubricated four-stage machine into 
a nonlubricated machine. This was a difficult under¬ 
taking but it is now felt that the development has 
been largely successful and although the machines 















97 


FOUR-STAGE NONLUBRICATED OXYGEN COMPRESSOR 



Figure 7. Carbon rings used on two-stage dry oxygen compressor. 


do not as yet have as long a ring life as desired, rela¬ 
tively little further development should he needed 
to make possible a nonlubricated oxygen compressor 
which will have as long a life as the commercial com¬ 
pressors available before the war. The compressor 
is compact and light in weight compared with com¬ 
mercially available machines. The program on the 
water-lubricated high-pressure oxygen compressor 
was never completed but was a part of, and merged 
with, the nonlubricated one. To cpiote from the Clark 
Brothers report, “Of all the projects covered by 
contract OEMsr-370, the development of a satisfac¬ 
tory portable oxygen compressor is the one which 
involved the most work, tedious attention to fine 
details, and many discouraging failures.” The speci¬ 
fications for the final nonlubricated high-pressure 
oxygen compressor are given in Table 2. 

The investigations relative to this compressor were 
hampered and delayed by many factors, some of 
which were caused by a failure to understand the 
variables involved and others of which were the 
result of material shortages. The project involved 
the testing of many and varied materials, some most 
difficult to obtain. The test work running from May 
1942 to May 1945 necessitated almost continual 
operation of two or more test compressors in order 
to cover the investigations required. 

The project breaks down into five distinct phases 
or sub-projects, each of which advanced the knowl¬ 
edge of the subject toward a clearer understanding. 


Table 2. Specifications Clark four-stage, 0-2,200 psi, 
vertical Dri-oxygen compressor. 


Type: Vertical, two- 

•crank, four-stage, tandem, single act- 

irg, nonlubricated, water-cooled. 

Model: DVO-2-4 

Compressor data: 

Suction pressure 

0 to 10 psi 

Discharge pressure 

2,200 psi maximum 

Capacity 

12 to 14 cfm at 14.7 psi and inlet 
temperature 

RPM 

860 

Approximate blip 

25 

Stage 

12 3 4 

No. of cylinders 

1111 

Bore 

5 in. 3p2 in. 1^6 in. D/io in. 

Stroke 

3 1 /2 in. 

Design features: 

Cylinder liners 

Highly polished chromium - plated 
bronze 

Piston rings 

Segmental Graphitar 2 and Stack- 
pole carbon H4-WA 

Dimensional data: 

Installation drawing 

103-157 

Overall length 

28 in. 

Overall width 

1914 in. 

Overall height 

6314 in. 

Approximate weight 

650 lb 

Accessories supplied 

Oil pump, oil gauge, water piping 
and flywheel grooved for V-belt 
drive 


The major premise was that any compressor built 
for the NDRC oxygen generating units should be a 
dry unit, that is, one which would operate without 
liquid lubrication. Most specifications for complete 
generating units provided that the oxygen charged 











98 


OXYGEN COMPRESSORS AND LIQUID OXYGEN PUMPS 


into cylinders should have a dew point of —80 F. 
If a water-lubricated compressor were used, bulky 
drying equipment would be necessary and it would be 
difficult to ascertain the quality of the drying. Some 
time, however, was devoted to a water and then a 
soap-and-water-lubricated compressor. However, a 
water-lubricated carbon ring compressor was soon 
found to be undesirable from the mechanical point of 
view as well as impractical from the standpoint of 
maintenance of standard dryness, and the sights were 
again set for the nonlubricant unit. 

The first phase of the work centered around a 
pilot model, single-cylinder test machine which served 
its purpose well in helping to define the type best 
suited for preliminary work. Several preliminary 
arrangements were tested and found to be unsatis¬ 
factory. 1 

The second phase covered the modification of the 
original full four-stage compressor, which may be 
said to have established the conditions for the third 
phase of the work. This work, the last on the original 
machine, was a complete investigation of the effects 
of piston ring design on ring wear in the fourth stage 
of the model. It might be noted that the first and 
second models of the original four-stage machine dif- 
ferd only in the positions of the third and fourth- 
stage cylinders in relation to the first and second- 
stage cylinders. This portion of the work also set 
the dimensions and general design of the first produc¬ 
tion model as used on the production generating units 
LP-1, LPS-2, and LPAS-3 (see Chapter 3). 

The fourth phase of the work covered the initial 
investigations on the production model. It consisted 
of determinations of the operating characteristics and 
faults of the machine. This work finally brought to 
light the “bugs” which had been causing the diffi¬ 
culties on all earlier models. 2 

With the discovery of the basic problems, the fifth 
and most fruitful phase of the work unfolded. 

Single-Cylinder Tests. At the time the work was 
started, certain definite ideas had been put forward 
as to the general design features desirable in a dry 
portable oxygen compressor. It was to be a four-stage 
unit, preferably with two cranks, in tandem, that is, 
with two or more pistons operating from one crank- 
throw. For the first two stages, segmental carbon 
rings operating on polished chromium-plated liners 
seemed to be within the realm of practical possibili¬ 
ties and would not be too great a gamble. However, 
the route to be followed for the third and fourth stages 
was very difficult and it was decided to try to deter¬ 


mine the optimum design for these stages by oper¬ 
ating a single-cylinder pilot machine. In so doing, the 
design work on the first and second stages could then 
be pushed ahead and the complete machine prepared 
for whatever design was decided upon. Further, by 
this method, any number of combinations could be 
quickly and easily tried out. 

The pilot device consisted of a modified garage-type 
air compressor having a 3^-in. stroke and a cylin¬ 
der casting adapted so that interchangeable liners of 
1-in. bore could be installed. The piston of the basic 
air compressor was used as a crosshead and arranged 
so that various types of 1-in. diameter plungers and 
pistons could be connected to it. Both liners and pis¬ 
tons could be changed easily and several different 
combinations were tried. 

By use of this device, the following combinations 
were investigated. 

1. A solid metal plunger operating in a graphite 
carbon liner. The results were extremely poor as 
the liner wore rapidly both from gas erosion and 
actual friction with the plunger. 

2. A silver impregnated carbon liner with a solid 
plunger. The results were about the same as in No. 1. 

3. A solid metal plunger operating in a brass liner 
using a water-lubricated graphite packing. Several 
different arrangements of lantern and regular rings 
were used. However, the results were not too satis¬ 
factory and the introduction of water lubrication in¬ 
volved considerable difficulties in the lubrication of 
the crankcase parts; consequently the work was 
dropped. 

4. A solid plunger operating in a brass liner and 
leather packing rings with water lubrication was 
tried. This, too, was dropped since considerable dif¬ 
ficulty was experienced with embrittlement of the 
leather as it dried out between runs. 

As a result of work on the single-cylinder pilot 
compressor, the decision was made to go ahead and 
build up a complete four-stage oxygen compressor. 
Idie design was to be such that either a water-lubri¬ 
cated or a dry machine could be made from the 
parts, the basic crankcase and running gear remain¬ 
ing the same. It was decided to build five complete 
units, bolding up all parts which might have to be 
changed as a result of later investigations. It had been 
all too apparent in work on the single-cylinder pilot 
machine that only part of the problems developed 
during the test work, and that to find the true results, 
conditions more nearly similar to actual operation 
would have to be maintained. 



FOUR-STAGE NONLUBRICATED OXYGEN COMPRESSOR 


99 


Original Four-Stage Compressor Type I 

It was assumed that the first four-stage compres¬ 
sor could be built with conventional segmental design 
carbon rings, operating against polished chromium- 
plated liners in the first and second stages, and that 
the last two stages could be changed and experi¬ 
mented with until a satisfactory combination was 
found. 

1 he machine which finally evolved was quite simi¬ 
lar to Figure 2 except that provision was made for 
mounting the third and fourth stage cylinders on top 
of the first and second stage cylinders. Figure 8 
shows the cross section of the production model and 
Figure 9 is a view of the production model. The run¬ 
ning gear is conventional, the only innovations being 
in the welded steel crankcase (used for lightness) 
and the use of the carbon rings. 

The machine was so arranged that the type of 
material in the liners, plungers, and rings of all 
stages could be varied quite easily. 

Following the assembly of the first two machines, 
more work was put on the third and fourth stages, 
as it was soon apparent that the first two stages were 
generally satisfactory for the material combinations 
tried. Briefly noted below are the combinations tried 
on the last two stages, classified under the material 
used on the first two stages. 

1. With no lubrication; using segmental carbon 
rings on first two stages. 

a. Third and fourth stage carbon liners using 
solid chromium-plated plungers. This ar¬ 
rangement was discarded due to rapid gas 
erosion of the liners with a consequent loss 
in capacity. 

b. Third and fourth stage carbon liners with 
carbon packing rings at the base of the liners 
again using a chromium-plated solid plunger. 
This arrangement, too, had to be discarded 
because of rapid wear and seriously reduced 
capacity. 

c. Brass liners on the third and fourth stages, 
with various combinations of brass, steel, 
chromium-plated steel, and various steel 
rings. In each case, the heat generated was 
of such a magnitude that the rings were an¬ 
nealed and collapsed. The wear on the liners 
was quite severe. This combination was 
dropped also. 


2. With water lubrication; using Micarta rings op¬ 
erating on chromium-plated first and second-stage 
brass liners. 

a. Solid Micarta plungers having annular 
grooves, using water lubrication. Serious 
leakage of water into the crankcase of the 



Figure 8. Cross section of final version production 
model, four-stage Clark Dri-oxygen compressor. 

































































































































































































































100 OXYGEN COMPRESSORS AND LIQUID OXYGEN PUMPS 



MAIN INSTRUMENT 
BOARD 


LOWER HALF OF 
CLARK EXPANSION 
ENGINE 


CLARK DRI-OXYGEN 
COMPRESSOR 


Figure 9. Clark Dri-oxygen compressor on model LPS-2 oxygen generating unit. 






















FOUR-STAGE NONLUBRICATED OXYGEN COMPRESSOR 


101 


compressor resulted but was easily corrected. 
Severe wear on the third and fourth stage 
liners resulted in rapidly diminishing ca¬ 
pacity, such that, in 20 hours, near zero ca¬ 
pacity resulted. Machine was found to he 
dangerous as it caught fire easily even when 
pumping air. 

b. 1 he same combination, using soap and water 
as a lubricant with no reduction of wear and 
considerable difficulty caused by gummy de¬ 
posits on plungers, rings, and valves. 

c. Micarta rings operating against brass cylin¬ 
ders, with both water and soap and water 
lubrication. Results were good as to ca¬ 
pacity, but mechanically the machine was 
poor, and it was a serious fire hazard. 

3. With no lubrication; using carbon rings on the 
first and second stage cylinders operating against 
chromium-plated brass liners. 

a. Carbon rings for both third and fourth stages 
were operated against plain, polished brass 
cylinder liners. The wear characteristics 
resulting were extremely poor since the brass 
was not hard enough to allow polishing of 
the rings. 

b. Chromium-plated third and fourth stage cyl¬ 
inder liners were then tried using graphite 
bronze rings, but ring wear was considered 
excessive and this material was dropped. 

c. Carbon rings operating against brightly pol¬ 
ished chromium-plated third and fourth stage 
liners were by far the most successful com¬ 
bination to this date, although results were 
rather difficult to duplicate. 

Following on the last combination, most of the 
work centered on refinements in the design of the 
carbon rings on all four stages and improvements in 
the surface finish of the chromium-plated bronze 
liners. The results of previous test work had been 
convincing enough to warrant standardizing on 
highly polished heavy chromium-plated brass or 
bronze liners, and, consequently, every effort was 
made to improve the machining and finishing opera¬ 
tions on these parts in order to eliminate inaccuracies 
and sources of error in tests. 

Considerable work was done on the design of 


the rings; step-cut, butt joint, and relieved rings were 
tried, and several different materials as well as nu¬ 
merous grades of carbon were investigated. A study 
of the effects of fourth-stage piston ring design was 
made relative to fourth-stage ring wear when using 
carbon material. Due to the extreme variations in 
the nature of the materials available, the quality of 
the machine work, and other variables, much dupli¬ 
cation of test work was necessary to establish whether 
material or ring design was the controlling factor 
influencing the wear. Since the object of this series 
of tests was to determine the optimum active life of 
the fourth-stage rings, only brief attention was paid 
to compressor performance. On each test, a rough 
check was made on capacity to ascertain the maxi¬ 
mum flow. 

As a result of these tests, it was discovered that 
certain methods of grooving the rings or relieving 
them would increase ring life, but it was immediately 
apparent that the unloading also cut the capacity 
greatly. It was necessary later to decrease the 
amount of unloading in order to restore the capacity 
of the machine. This, of course, again decreased the 
ring life. 

Table 3 shows the various tests made, the designs 
used, and the results. Figure 10 shows details of the 
various ring designs used. These results served to 
establish certain design requirements necessary for 
a satisfactory unit and to give some background on 
carbon piston ring design. It was clear that carbon 
rings, if dry, could be run successfully on chromium- 
plated liners under the following conditions: 

1. If an excess of water is not present, the presence 
of actual drops of water causes the carbon dust to 
“ball" up and score the rings. (Flooding with water 
permits successful operation.) 

2. If operating surfaces are polished to as fine a 
surface as can be obtained commercially. 

3. If unit ring loadings are not excessive. The 
actual finite values were not established although 
there is a decided increase in wear on the fourth- 
stage rings over those in the third stage. 

Furthermore, an oxygen compressor using carbon 
rings operating dry is safe to use for handling 2,000 
psi oxygen if adequate cooling is provided. 

It was found that the blow-by on the third and 
fourth-stage rings was higher than had been esti¬ 
mated and consequently the first machine was some 
20 per cent under capacity. It was, therefore, de¬ 
cided to redesign the entire compressor and to change 




102 


OXYGEN COMPRESSORS AND LIQUID OXYGEN PUMPS 


cylinder sizes in order to bring the capacity up to 
that needed for the various oxygen units. This re¬ 
design was, of course, necessitated by the fact that a 
higher capacity machine was required for the pro¬ 
duction models. 

While the redesign work on the oxygen compres¬ 
sor was going forward, some further tests were made 
on the old model. These were interesting and in¬ 
structive. 

The suggestion had been made regarding the 
possibility of using a polymerized fluoro-carbon 
compound [TFE] for piston rings. Consequently, 
samples of the material were procured, rings made 
up, and several tests run. Following is a brief con¬ 
densation from the test report on these runs. 


A run was made at 2,000 psi discharge 

with 300 psi 

suction, giving the following results: 


1. Hours duration 

24 

2. Average discharge temperature 

300 F 

3. Test fluid 

Air 

4. RPM 

900 

5. Ring wear 



a. Bottom 2 rings completely gone. 

b. Next 4 rings worn to 0.070 in. radial thick¬ 


ness. 

c. Top rings in fair condition. 

It was concluded that the top rings had never made 
a complete seal with the cylinder wall, and conse¬ 
quently had not worn. Investigation disclosed that 


Table 3. Type I oxygen compressor carbon ring life tests. 


No. 

Hr 

Wear 
in.per hr 

Ring 

material 

Ring size and design 

Notes 


1-3 

87 

.0006 

Graph. 2 

Ys in. ID butt joint 5A 

Maximum capacity 

11.0 


60 

.0008 

Graph. 2 

yi in. ID butt joint plain 2A 

Hardened Cl liner 

8.0 

1-5 

24 

.0008 

Graph. 2 

in. ID l / 2 in. step-cut face 4B 

Hardened Cl liner 

5.0 

1-6 

12 

.007 

Morgan. 

5/g, in. ID step-cut plain 2B 

Hardened Cl liner 

9.7 

I-6A 

12 

.006 

Graph. 2 

Top 4 step-cut plain 2B. §4 in. 

ID 4-11 grooved IB 

Hardened Cl liner 

8.3 

1-13 

48 

.00045 

Graph. 2 

Ys in. step-cut plain 2B 

Variable disch. 

12.0 

1-14 

22 

.00013 

Graph. 2 

1 4ie in. ID one piece 2C 

Variable disch. 

15.7 


Notes: 

1. A total of 16 tests were run in this series totaling over 1,200 hr. The balance, not shown, and totaling 200 l)r were abortive and 
since they have no bearing, they are not presented. 

2. Wear, in. per hr, represents average radial wear or reduction in radial thickness of the three segments of the top ring. 

3. All tests run at constant discharge except as noted. 

4. All tests run on bright chromium-plated bronze liners. 

5. All tests run on dry air, dew point not known. 

6. All rings were %6 i n - thick except as noted. 

7. Materials: Graph. 2 — Graphitar 2, U. S. Graphite Company; Morgan. — Morganite Grade 8762, Morganite Brush Company. 

8. Figures shown under notes indicate maximum capacity cfm. 

9. For ring styles, see Figure 10. 


Tests on TFE Material. Fourth-stage rings only 
were fabricated and tested. The dimensions of rings 
on installation were in every case 0.0625 in. ID, 
1.062 in. OD, and 0.437 in. thick. All tests were 
made on the Clark-NDRC, four-stage oxygen com¬ 
pressor having a highly polished chromium-plated 
brass fourth-stage cylinder liner. The compressor 
was operated at 900 rpm. 

The first trial run was made with a discharge of 
2,000 psi and a suction of 400 psi on this stage. Im¬ 
mediately following the start of the test, the dis¬ 
charge temperature went to 480 F. The unit was 
shut down and disassembled for inspection. 


particles of the missing rings had actually worked 
down past the carbon guide into the first-stage cyl¬ 
inder, and through the whole machine to such an 
extent that the carbon rings on the third-stage piston 
were gummed up in their grooves. 

Another trial run under the same conditions indi¬ 
cated the same trend. Ring wear was severe, capacity 
fell off rapidly, and the discharge temperature was 
abnormally high. 

General observations on the TFE material were: 

(1) the material was so soft that any small particles 
touching it could easily be forced into its surface, 

(2) there is evidence of a small amount of thermo- 







FOUR-STAGE NONLUBRICATED OXYGEN COMPRESSOR 


103 


A 


B 


C 



00X 4 10 ie THICK 


BUTT JOINT 
3 SEGMENT RING 



5 

STEP JOINT 
3 SEGMENT RING 



ONE 

PIECE RING 



NO. I 


'32 


GROOVE 




■vi/- 

1 " 





32i_ 

'—i 

NO. 2 

NO. 3 

T 

->» 

Li." 




16 


NO. 6 




NO. 5 


Figure 10. Details of experimental carbon rings. 

































104 


OXYGEN COMPRESSORS AND LIQUID OXYGEN PUMPS 


plasticity causing binding of these rings in the ring 
grooves, and (3) the resistance of this material to 
wear is greatly inferior to that of carbon rings 
tested under identical conditions of operation. 

These results, coupled with the information re¬ 
ceived as to the possible toxicity of the material, led 
to temporary discontinuance of further work on the 
TFE compound. 

On advice that the TFE material was not toxic 
in the quantity which would he found in oxygen 
pumped by a compressor having rings of this mate¬ 
rial, two further checks were made. 


Plain TFE on Wear Test Machine 



Plain 

Graphitar 2 


TFE 

Carbon 

Unit load psi 

60 

600 

Face velocity ft/min 

500 

500 

Face temperature (metal) F 

120 

230 

Metal surface 

Chromium-plated 

Cast iron 

Wear rate in./hr 

.036 

.001 


Ring Tests on Three TFE Samples in Oxygen on 
Oxygen Compressor 

TFE Material Results 

Unmodified Dupont Teflon Wore rapidly and flaked away 
Dupont Teflon, 40% Collapsed under load, wore much 

copper-filled faster than carbon 

Dupont Teflon, 40% Fragmented badly when cut and 

graphite-filled could not be machined into rings 

Safety and Fire Hazard Test. Before finally set¬ 
tling on the future design two important tests were 
made on the old units, one to determine the safety of 
the design, the other to check on the actual piston 
arrangement. Since the original machines were to 
he scrapped, it was decided to test one unit to de¬ 
struction. Therefore, at the close of a normal run 
operating on oxygen, the discharge pressure was 
raised to 2,900 psi, and at the end of one-half hour 
under such conditions, the cooling water was shut off, 
whereupon the discharge temperature climbed to 
600 F. At this time the discharge line started to 
smoke and the compressor was shut down immedi¬ 
ately. Before it stopped turning, the fourth-stage 
cylinder head let go violently. The peak temperature 
and pressure could not he observed. No flame was 
observed. 

Upon investigation of the remains, it was found 
that the cylinder head was completely shattered and 
that the top part of the bronze piston had literally 
flowed into the discharge valve. The top carbon ring 
had disintegrated. All ferrous parts such as the valve 
springs and disks seemed to have burned completely. 
The cylinder was ripped open and the studs pulled 
out. 


It was concluded that the general design should 
he safe for operation under the conditions required, 
provided an ample supply of cooling water was avail¬ 
able, discharge pressures were kept under 2,300 psi, 
and ferrous alloys not susceptible to easy combustion 
in oxygen were used for valve disks and springs (one 
of the 18-8 stainless steels would he satisfactory). 

The initial design on the four-stage compressor 
mounted the first and fourth and the second and 
third-stage pistons in tandem; this resulted in the 
second-stage discharge occurring while the third- 
stage cylinder was discharging. It was thought that 
better operating results would follow if the first and 
third, and the second and fourth-stage pistons were 
combined; this would mean that in every case a cyl¬ 
inder would he discharging during the suction stroke 
of the next stage. 

One of the original machines was, therefore, re¬ 
built in this manner and the test work on it was quite 
detailed and elaborate. It is of sufficient importance 
to he considered the third definite step in the develop¬ 
ment. 

Original Four-Stage Compressor, Type II 

The third series of investigations on the oxygen 
compressor relates to the work on what came to be 
known as Type II of the original four-stage com¬ 
pressor. It was thought better to arrange the pistons 
and cylinders on the compressor so that the first and 
third, and the second and fourth stages were in tan¬ 
dem. To settle the question definitely, one of the 
original machines was so modified. 

First tests on this machine indicated slightly im¬ 
proved compressor performance as a result of the 
change, and, although the improvement was only 
slight, it was decided to use this design on the pro¬ 
duction models then being drawn up. 

At this point, it was quite evident that the key 
problem on this project was to find a satisfactory 
fourth-stage piston ring design and/or material. The 
rate of wear on all stages was satisfactory except on 
the last stage. Stated in definite terms, the situation 
at this point was that the Army Air Forces and the 
Engineer Board would he satisfied with a minimum 
life of 500 to 600 hr on a set of rings when operating 
under cylinder charging or variable discharge con¬ 
ditions. No standards other than these had been set, 
and these were based primarily on opinion. How¬ 
ever, the tests to this date had shown a much shorter 
life than this for the fourth stage, with the third stage 
approaching this standard and the first and second 
bettering it. 




105 


CLARK DRI-OXYGEN COMPRESSOR 


Before scrapping this model, it was used to de¬ 
termine more carefully the influence of design and 
material on ring wear, and the actual amount of ring 
wear under severe operating conditions. If the ma¬ 
chine were operated under normal conditions, that is, 
variable discharge as in charging cylinders, each test 
would take up an extremely long time, so it was de¬ 
cided to accelerate the test work by operating at con¬ 
stant discharge, 2,000 psi. 

To be able to correlate the two different conditions, 
two tests were made using the same rings, one at 
constant discharge and the other at variable dis¬ 
charge. Actual results indicated a difference of 1 to 3 
in resultant ring life. 

Based on this information, it is assumed that under 
normal operating conditions ring life three times that 
found at constant discharge could be expected. 

A total of twenty-five separate tests were made on 
this machine. The most useful data can he summa¬ 
rized : 

1. Reduction of the ring face thickness to % 6 in. 
from 7 / 16 in. apparently stabilized the wear rate at 
0.00008 in. to 0.0011 in. (Tests 21 to 24.) 

2. Of the three materials tested, Graphitar 2 ap¬ 
pears to be the best. 

3. Unloading the rings as in tests 21 to 24 could 
explain the apparent improvement over the rate 
shown in test 20. 

4. Test 24, which had three unloaded rings at the 
top with eleven plain rings below, might have shown 
up better by reason of this arrangement. 

During this and the previous series of tests, the 
following influencing factors were investigated to 
ascertain whether they were affecting the results. 

1. Ring material (no really definite evidence). 

2. Material of liner (no evidence). 

3. Type of plating on liner (no evidence). 

4. Type of finish (high polish best). 

5. Carbon dust filters (little evidence). 

6. Piston and ring assembly (some hut no definite 
evidence). 

7. Piston guides (found to be necessary). 

6 4 CLARK DRI-OXYGEN COM¬ 
PRESSOR 

Probably the most instructive and thorough test 
work on the oxygen compressor was carried out on 
the production model, which was called the Clark 
Dri-oxygen compressor. 

Early in 1944, the final design was worked out and 


put into production. 2 Figure 8, a cross section, shows 
all of the details. The general construction was little 
changed from the previous model, the major changes 
being in the size of the first- and third-stage pistons. 
The running gear was changed slightly but only in 
minor details not affecting the operation. 2 Table 2 
gives the specifications of the unit. 

Prominent among the changes on the new machine 
were: 

1. Addition of solid top and bottom carbon guides 
on the third and fourth-stage pistons. 

2. Increase in the number and decrease in thick¬ 
ness (to %q in.) of rings on the last two stages. 

3. Use of beryllium copper on fourth-stage piston. 

4. Lengthening of third- and fourth-stage piston. 

5. Use of individual heads on first- and second- 
stage cylinders. 

6. Lap-fitting and polishing of third- and fourth- 
stage liner. 

7. Use of two segmental compression and one 
heavy segmental guide ring (all of carbon) on the 
first two stages. 

The machine built was based on the theory that 
the best results would be obtained using carbon or 
some similar material operating dry on bright chro¬ 
mium-plated bronze. All test work was to be devoted 
to refining the design, and investigating the influence 
of ring design and material on the operating life of 
the rings. 

It was found almost immediately that the results 
on the first two stages were uniformly good, con¬ 
firming the results on the early four-stage and the 
two-stage dry oxygen compressor. Apparently, the 
unit-loading pressures are such that undue wear does 
not result. 

Early in the work, however, it was clear that 
much thought and time would have to be spent on the 
third and fourth stages, as difficulty was experienced 
in duplicating results, and wear seemed to be abnor¬ 
mally severe. 

The work on this machine can be considered in 
three separate categories. The first was the mechani¬ 
cal, the second consisted of exploratory ring wear 
tests, and the third covered a detailed analysis of the 
problems concerned with ring wear. Incidentally, 
the latter has been the most fruitful with definite 
positive results. 

The first work on the machine might properly be 
called the shakedown period, wherein all facets of 
the machine performance were investigated and re¬ 
medial action taken where necessary. This work, 




106 


OXYGEN COMPRESSORS AND LIQUID OXYGEN PUMPS 


mainly routine and necessary on most new equip¬ 
ment, was soon finished and deserves only passing 
comment. The items covered were: 

1. Design changes to obtain satisfactory crankshaft 
material and bearing liner combination (war short¬ 
ages). 

2. Change-over to babbitted crossheads necessi¬ 
tated by reduction of lube oil flow around piston rod. 

3. Material changes on fourth-stage pistons. 

4. Cylinder design changes in order to drain cast¬ 
ing completely of cooling water. 

5. Addition of thermally operated alarm system. 

6. Horsepower and capacity tests. 

7. Ring life tests operating with oxygen on first 
trailer-mounted oxygen units. 


Of all of these, only numbers 6 and 7 require addi¬ 
tional comment. 

Figures 11, 12, 13, 14, and 15 depict the operating 



SUCTION PRESSURE — INCHES Hg 

Figure 11. Dry oxygen compressor capacity vs suction 
pressure at various speeds. 





Figure 12. Dry oxygen compressor capacity vs rpm at 
2,000 psi discharge. 



SUCTION PRESSURE — INCHES Hg 


Figure 13. Dry oxygen compressor brake horsepower 
vs suction pressure at 860 rpm. 









CLARK DRI-OXYGEN COMPRESSOR 


107 



Figure 14. Fourth-stage ring wear, top five rings vs 
operating time using three-piece segmental Graphitar 
No. 2 (Pbl 2 impregnated) (none unloaded) dry oxygen 
constant 2,200 psi discharge. 


UJ 

cr 



Figure 15. Average instantaneous capacity vs operating 
time using three-piece segmental Graphitar No. 2 
(Pbl 2 impregnated) (none unloaded) dry oxygen constant 
2,200 psi discharge. 

characteristics of this production-type oxygen com¬ 
pressor when operating at its maximum design dis¬ 
charge pressure. The reason for checking at suction 
pressures above atmospheric is that it was expected 
it would be necessary to raise the suction pressure to 
counteract loss of capacity caused by ring wear. 

The horsepower shown by Figure 13 is at least 50 
per cent over that expected for an oil-lubricated ma¬ 
chine for these conditions. The difference can only 
be ascribed to increased frictional losses. 

Concerning item 7 above, the first endurance test 
on the first production model compressor was made 
on one of the Model LP-1 trailer units. The fourth- 
stage ring life on this test did not exceed 60 hr with 
the machine operating under cylinder-charging con¬ 
ditions (variable discharge). The charging rate or 
capacity of the machine dropped below practical lim¬ 
its after 60 hr. This was far from the results ob¬ 
tained during the last of the previous tests detailed, 
where ring life approaching 250 hr had been ob¬ 
tained. 

A long series of tests was made, varying many 
conditions. Filters were tried between stages, as 
well as operation on dry air, and in every case the 


ring life was found to he far shorter than previously 
experienced. Several methods of unloading or re¬ 
lieving the rings were tried, but a combination which 
gave reasonable wear would result in extremely low 
capacity. At that point it was concluded that for 
some reason previous tests had been in error, or that 
some insignificant but vital detail had been changed. 
To prove or disprove such conclusions, further tests 
had to he made. 

The last work consisted of two groups of tests 
made on a compressor set up on a test block for ease 
of dismantling and assembly. The first tests in this 
series were made on oxygen, dry air, and atmospheric 
air, and were run to test out certain theories con¬ 
cerned with ring design and moisture content of the 
fluid being pijmped. 

The last group of tests in this series related to ma¬ 
terial investigations, ring design, and rechecking ear¬ 
lier work. 

The following conclusions are valid for the further 
tests, which are all listed in Table 4. 

1. No definite proof has been presented as to the 
difference, if any, in ring wear when pumping dry 
oxygen and dry air. 

2. A definite difference in ring wear, at least 3 to 
1, has been shown between operation on air contain¬ 
ing moisture and dry oxygen. 

3. Rate of wear on any given ring and any stated 
material is a direct function of: 

a. Ring design (unloading for example). 

b. Ring and piston assembly. 

4. Rate of wear on any given ring and ring de¬ 
sign is a function of ring material and/or liner mate¬ 
rial and plating. 

5. Instantaneous capacity is not apparently a func¬ 
tion of ring or liner material but is definitely a func¬ 
tion of ring and ring assembly design. 

6. Cumulative capacity is by inference a function 
of: 

a. Ring and ring assembly design. 

b. Ring and/or liner material as it affects wear. 

7. It was quite apparent from the inspection of the 
tests that test C-10 represents by far the greatest 
advance in the search for a suitable ring material for 
use on these dry oxygen compressors. Army Air 
Forces had been experiencing extremely severe and 
even critical wear on the carbon brushes of the air¬ 
craft generators and motors operated at elevations of 
30,000 ft or higher. As a result of investigations, it 
was felt that the increase in wear at higher elevations 
was caused by absence of moisture or decrease in 







108 


OXYGEN COMPRESSORS AND LIQUID OXYGEN PUMPS 


Table 4* 


Wear Ring 

No. Hr In/Hr Material Ring Design_Notes 

A-2 

67 

All 

gone 

Graph 2 

20^1 

Variable Discharge 

O2, Filters Used 

A-3 

90 

.001+ 

Graph 2 

20^1 

Dry air. low 

flow, l4 cfm <3 9 It 

A-5 

50 

Very 

bad 

Graph 2 

20 [-51 

O2, N.G. Liners scored 

A-6 

51 

.006 

Graph 2 

20 [3 

02, 13.2 cfm O 10 lb 

A-7 

24 

.007 

Graph 2 

20 r 5 ~l 

O2, Poor flow 

B-l 

62 

.0005 

to.001 

Graph 2 

ulZ] , 2tvE),lulZL 

Dry°a?r Capacity good 

B-2 

29 

.00075 

Graph 2 

20 

-250°F Poor oapacity 

Dry air liner scared 

B-3 

27 

.00007+ 

Graph 2 

20 S 

Atmos. New liner 

Air Plunger broke 

B-4 

48 

.0003 

Graph 2 

20 dZl 

Atmos. Air 

B-5 

66 

.0006 

Graph 2 

20 nn 

Atmos. Air 12.4 - 8.0 cfm 

B-6 

72 

.0021 

Graph 2 

20 [ZD 

02 No Filters 20 - 16.0 cfm 

C-l 

26 

.0013 

Graph 2 

8 [czf, 12 [-5], 

O2 Uniform capacity 

C-1A 

14 

.004 

Graph 2 

8[2J / J2 c 3 . 

O2 Uniform capacity 

C-IB 

9 

.0014 

Graph 2 

8 ^. 12 dH, 

O2 Uniform capacity 

C-2A 

50 

.0005 

Graph 2 

15 f 9 See Fig 17 • 

Fair Flow 

O2 Ring breakage 

C-5 

92 

.00013 

Graph 2 

20 £ —\ & 

n 11,5 - 8.5 

VJ 2 Moly plate liner 

C-4 

80 

.0008 

Nat ‘1 

l@, 1[Z],18S, 

'cfe 

C-5 

16 

.0009 

Graph 2 

9 # 10 See Fig 17 

Q2 Reasonable capacity 

C-6 

41 

.002 top 
.001 2nd 

Graph 2 X 

20 GD 

O2 12.3 - 9.1 cfm 

C-7 

18 

Bad 

Graph 2X 

r—,<9 

20 cEd 

High breakage 

O2 All rings 

C-8 

85 

. 0^047 

Graph 2JL 

^ 

O2 11.8 - 8.5 cfm 

C-10 

142 

.00049 

H 4 -WA 

20 

O2 12.0 - 6.3 cfm 

C-ll 

57 

.00098 

K 4 -WA 

20^ 

0 11.0 to 9.0 cfm 


* Ring designs are shown in Figure 16. Typical ring arrangements are shown in Figure 17. See notes on pages 109 and 112. 








































CLARK DRI-OXYGEN COMPRESSOR 


109 


the amount of moisture in the atmosphere surround¬ 
ing the brushes. Work along this line was consider¬ 
ably detailed and finally led to the use of lead iodide 
and barium salts to impregnate carbon of grades 
similar to those used in test C-4 and C-10. One of 
the interesting results of tests reported by a carbon 
company is that the presence of oxygen decreased the 
wear. (D. Ramadoff and S. W. Glass, paper 44-208 
before AIEE meeting August 29, 1944, Los Angeles, 
California.) 

8. Test C-3 appears, off-hand, to give an answer 
to the ring-wear problem. However, what had actu¬ 
ally happened was that the special plating on the 
cylinder liners wore out rather than the rings; after 
the plating had worn through, the rings wore very 
rapidly. The plating was a special molybdenum coat¬ 
ing developed by the Bell Telephone Laboratories for 
another NDRC problem. (It was planned also to use 
a stellite plating as developed by the Industrial Re¬ 
search Laboratories in Los Angeles, California, but 
no test has been made because of difficulties expe¬ 
rienced in obtaining a smooth surface in the bore of 
the plated liner.) 

The following conclusions were reached: 

1. There may be one material and liner combina¬ 
tion which will give the lowest absolute wear rate 
independent of ring, piston, assembly, or compressor 
characteristics. 

2. There may be one piston and ring assembly and 
ring design which will give the optimum performance, 
measured in cubic feet hours, for any given material 
or compressor. 

On run B-l, listed in the table, after 61.8 hours 
ring wear on the first six rings was as follows: 


Seg 

ment (inches) 

Avg. Rate of Wear 

1 

2 

3 

First 40 hr 

Last 21 hr 

0.103 

0.105 

0.156 

0.0015 

0.0028 

0.076 

0.087 

0.090 

0.001 

0.002 

0.042 

0.059 

0.090 



0.038 

0.041 

0.057 



0.008 

0.033 

0.050 




Capacity at finish 15.6 cfm with 12 in. Hg suction. 


3. It is entirely possible that no better material 
than some form of impregnated carbon will be found. 
For years past, various forms of carbon have been 
used for non-lubricated rubbing surfaces and for non- 
lubricated bearings. A case in point is the use of 
carbon for motor and generator brushes. 

Naturally, the use of carbon rings impregnated 
with lead iodide raised the question of toxicity. Some 
rough checks have been made on oxygen pumped 


using these rings to determine the extent of contami¬ 
nation with lead. The following is an excerpt from 
the contractors’ laboratory report on the first test. 

Piston ring material H4-WA and K4-WA, examined 
spectrographically contained carbon and lead as the major 
materials, with traces of iron, aluminum, copper, and vana¬ 
dium in order of abundance. Lack of adequate laboratory 
facilities prevented more than a qualitative examination of 
this material. 

An examination of the oxygen pumped by a compressor 
using this material for 4th-stage rings was made by bleeding 
directly from the compressor discharge line without filters, 
10 cubic feet of gas through three Milligan wash bottles in 
series. The gas flow rate was approximately 2 cubic feet 
per hour. 

The total fluid content of the wash bottles, originally 
450 ml. of 4% (vol.) of nitric acid solution, was evaporated 
to 10 ml., and 0.1 ml. of the concentrate evaporated to dry¬ 
ness on spectographic carbon. The sample of concentrate 
contained less than 0.0001 milligrams of lead per cubic foot. 

Since the States of California, Connecticut, and the U.S. 
Public Health Service, state that the safe concentration limit 
is 0.0043 milligrams of lead per cubic foot, this oxygen 
should be safe to breathe. In our opinion provisions must be 
made, however, to trap out massive dust particles. 

The generally accepted maximum permissible concentra¬ 
tion of lead compounds in the air breathed by workmen is 
0.15 milligram lead equivalent per cubic meter, or about 
0.004 mg. per cubic feet. There can be no valid objection on 
the basis of possible health injury to pumped oxygen con¬ 
taining 0.001 mg. of lead per cubic feet, particularly because 
the breathing of this oxygen does not take place 8 hours a 
day for months and years while the accepted standard quoted 
above does contemplate such prolonged exposure. 

Traces of iodine or iodine compounds accompanying the 
lead are of much less toxicological importance and may be 
dismissed as insignificant so long as their concentration does 
not exceed a few times the lead figure stated above. 

Notes Pertinent to Fourth-Stage Ring Tests 
Presented in Table 4 

1. All tests were run at 2,200 psi discharge using 
highly polished chromium-plated bronze liners and 
butt joint y iG in. OD x % in. ID x s / 16 in. thick car¬ 
bon fourth-stage rings except as noted. 

2. Tests run using dry air, dry oxygen, or atmos¬ 
pheric air (dew point above -j-40 F). Where a tem¬ 
perature is given, this indicates approximate dew 
point. 

3. Ten different ring designs were used and are 
shown in Figure 17 along with the basic ring from 
which these were evolved. The column labeled “Ring 
Design” indicates the number and type ring. Reading 
from left to right, figures presented indicate the posi¬ 
tion from the top of the piston, as in test C-4; the 
characters indicate that the top ring is design 8, the 



110 


OXYGEN COMPRESSORS AND LIQUID OXYGEN PUMPS 


BASIC RING 3 SEGMENT BUTT JOINT 



RING MODIFICATIONS SECTION THROUGH A-A 


NO. I 


.030" 



NO. 5B 



ioo r 


050 7 


NO. 3 



NO. 4 


. 020 ' 




—" 

r* - .015 


N0.5C 


U- .015" 

,oi3"^rfi- 


o,ar Pi‘ 


I*-.015" 


N0.6 


020 


. 4 ^ 


* 0I5 TjT“- 

-H K.020" 


N0.6A 


.1 


.020 


/77 

¥-t 

r*~. 020 




,°° r ^ 


.050" 

1.060" 

NO. 5 

r 

L ^ 



K.oio 


NO. 7 



NO. 5 A 


HACK SAW GROOVE 



Figure 16. Fourth-stage ring design. 































































CLARK DRI-OXYGEN COMPRESSOR 


111 




NO. 10 



4 th STAGE PLUNGER 
ANO RING SET - UP 
FOR TEST C-5 


NO. 9 



4 th STAGE PLUNGER 
ANO RING SET-UP 
FOR TEST C-2A 


Figure 17. Fourth-stage piston ring set-ups. 





































































































112 


OXYGEN COMPRESSORS AND LIQUID OXYGEN PUMPS 


second ring is design 1, while the remaining eighteen 
are design 8. 

4. Notes indicate comments or special equipment. 
Capacity figures indicate starting rate and completion 
rate. 

5. Ring wear is the radial wear or decrease in 
segment radial thickness. It is total wear in inches 
divided by total time hours run. The figure shown 
is for the top ring except as noted. 

6. Ring materials are as follows: 


Graphitar 2 
Graphitar 2X 


National* 


H-4WA* 


K-4WA* 


Manufactured by U.S. Graphite 
Company 

Graphitar 2 impregnated with 
Pbl 2 by Clark Bros. Com¬ 
pany 

A graphitic carbon impregnated 
with barium salts and manu¬ 
factured by National Carbon 
Company 

A graphitic carbon Grade H-4 
impregnated with Pbl 2 and 
manufactured by the Stack- 
pole Carbon Company 

A non-graphitic carbon Grade 
K-4 impregnated with Pbl 2 
and manufactured by the 
Stackpole Carbon Company 


* These special materials were developed by the companies shown 
for a special service for Army Air Forces. They have the peculiar 
property of wearing better than ordinary graphitic carbon where the 
surrounding atmosphere is practically devoid of moisture (dew points 
less than —40 F, for example). 


6 5 LIQUID OXYGEN PUMP 

In the oxygen industry it has been customary to 
produce gaseous oxygen of desired purity, which is 
then led to a compressor where it is brought to a 
pressure of 2,200 psi for delivery into cylinders. It 
appeared that considerable advantage would be se¬ 
cured if the oxygen compressor could be eliminated. 
What was desired was a high-pressure oxygen gas 
unit which could be used for charging cylinders di¬ 
rectly without the use of the customary oxygen com¬ 
pressor. This result has been achieved by the devel¬ 
opment of a pump capable of taking liquefied oxygen 
from the boiler and injecting it directly into the heat 
interchanger system, where it emerges at any desired 
pressure at room temperature. 6 


In order to produce high-pressure oxygen gas di¬ 
rectly, it was proposed to withdraw liquefied oxygen 
from the boiler and introduce it into a channel of the 
heat interchanger system under pressure, the limit 
of this pressure being any value corresponding to the 
pressure desired in the tanks of oxygen to be charged 
at ordinary temperature. The change of oxygen from 
the liquid state to a gaseous state at ordinary tem- 




SPRING 


VALVE 

ACTUATING ARM 


BAKELITE HEAT 
BARRIER 


BLOCK FOR INLET 
RT) AND 

EXHAUST VALVES 


PUSH RODS 


Figure 18. Liquid oxygen pump—front view. 


perature and high pressure takes place in the inter¬ 
changer through the interchange of heat with the in¬ 
coming high-pressure air to be liquefied and sub¬ 
jected to fractionation. The injection has been 
brought about by the use of what is called for pur- 


















LIQUID OXYGEN PUMP 113 


poses of designation “Liquefied Oxygen Injector 
Pump.” The pump is operated from a branch line 
from the high-pressure air supplied to the unit for 
purposes of liquefaction and subsequent fractionation. 

Details and Drainings. The pump consists of two 
parts, a cylinder and a piston which periodically re¬ 
ceive supplies of liquid oxygen from the boiler for 
injection into the intercharge system. The force nec¬ 


essary to bring about the injection is obtained from 
a single-acting piston device without piston rod pack¬ 
ing, actuated by the high-pressure gas. The admis¬ 
sion of high-pressure gas to the power cylinder and 
its exhaustion therefrom are controlled by a valve 
system. Photographs of the assembled pump with 
the case removed are shown in Figures 18, 19, and 20. 

On the left of Figures 18 and 19 are the cases for 


BRASS CASE 3" OD POWER CYLINDER - 
FOR POWER PISTON NO PISTON ROD 
AND VALVE GEAR PACKING NEEDED 




VALVE 

"MECHANISM 

VALVE 

ACTUATING 

MEMBER 

ATTACHED 

TO PISTON 

ROD 

HEAT 

•INSULATING 
MEMBER 
4“ OD 

SPRINGS 
TO CAUSE 
RETURN 
STROKE 


LIQUEFIED 

OXYGEN 

CYLINDER 


CASE FOR OXYGEN 
CYLINDER THROUGH 
WHICH EFFLUENT 
CIRCULATES 


HIGH PRESSURE 
VALVE THROUGH 
WHICH LIQUEFIED 
OXYGEN IS INJECTED 
INTO INTERCHANGER 


Figure 19. Liquid oxygen pump—side view. 


n 




7 ir 


if If 



GRAPHITE 
, KOROSEAL 
11 IN BETWEEN 


kJjy 


THREE-PIECE 
fl-'-SELF-SEALING 
POWER PISTON 

’^“PISTON CONTACT 
PIECE TO PISTON 
ROD 

SIMPLE STUFFING 


LEAD RETURN 
BOILER 
PORTED VALVES 
LIQUID OXYGEN 
INLET 


.LEAD TO BOILER 


Figure 20. Liquid oxygen pump—disassembled. 


the upper and lower parts of the pump. The upper 
part is the power end, which is designed for operation 
with 3,000 psi air supplied from a branch line of the 
inlet air to the unit. The exhaust is released within 
the brass case above the 2-in. canvas-backed bakelite 


































114 


OXYGEN COMPRESSORS AND LIQUID OXYGEN PUMPS 


UJ 

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LIQUID OXYGEN PUMP 


115 


member or heat barrier. The piston rod runs the 
length of the pump, being in contact at the power 
end with a compound piston represented at the right 
in Figure 20. The power piston operates in a liner of 
hardened nitralloy with superfinished surface, the 
body of the cylinder being brass. The pump is single 
acting and is therefore provided with one inlet valve 
and corresponding exhaust valve. Both valves are 
contained in the block as indicated in the figure; they 
are operated by push rods. Opening and closing are 
accomplished by pressure from a push rod mecha¬ 
nism, actuated by a loaded spring. The motion of the 
latter from one side to the other is produced by a 
cam and roller on the piston rod as shown. In the 
latest model of the pump the lever piece operating the 
push rods is hinged on the inlet side. This is for the 
purpose of holding the inlet valve open until the 
power stroke is complete, when a latch releases the 
hinged portion an instant before the exhaust valve is 
opened through the action of the cam. There are 
four springs that provide for the return stroke. 

The oxygen cylinder is constructed of hardened 
beryllium-copper alloy. The original design of the 
oxygen piston has passed through several changes. 
Originally the attempt was made to use hardened 
beryllium-copper alloy with a ported valve inlet. Due 
to an apparently large increase in friction at —300 F 
for all metals investigated, this proved to be imprac¬ 
tical. The most desirable type of piston would be 
one in which the leak along the clearance between 
cylinder wall and piston is independent of the pres¬ 
sure under which the oxygen is being injected into 
the heat interchange system. Realization of this type 
of piston involves some difficulties, owing to the 
properties of materials at low temperature. 

The type of piston employed in the high-pressure 
drive is self-sealing on the power stroke and exhibits 
no appreciable friction on the return stroke. The 
latest oxygen piston has something of the same char¬ 
acteristics. In neither case is a piston packing-gland 
employed. 

Figure 19 shows the valve mechanism as it ap¬ 
pears for 180 degrees of rotation relative to the rep¬ 
resentation in Figure 18. Some details of the con¬ 
struction are shown; for example, the power piston 
is shown with its three parts separated. Contact be¬ 
tween the piston rod and the piston is not permanent, 
the piston rod end being merely pressed against a 
hardened steel piece connected to one of the brass 
parts of the piston. Two sets of graphite rings, with 
the middle member of Koroseal, comprise the piston 


rings. The four graphite rings are soaked in light 
lubricating oil and provide the necessary lubrication 
as well as constituting suitable support for the Koro¬ 
seal. The degree of contraction of the compound 
piston under pressure is brought about by the use 
of shims at each end. A spring surrounds the piston 
rod inside the cylinder and serves to return the pis¬ 
ton, and also to keep the three parts of the piston in 
contact at all times. In the lower part of the figure 
the original beryllium-copper piston is shown. This 
is connected to the piston rod by means of a simple 
universal joint, a feature which has been adhered to 
throughout all the attempts to perfect a satisfactory 
oxygen piston. 

Figure 21 indicates the disposition of parts of the 
model unit in which the pump is incorporated. This 
model unit is designed to produce either liquid oxy¬ 
gen (18 lb per hr for 300 lb per hr air circulated) or 
high-pressure gaseous oxygen (35 to 40 lb per hr). 
(See Keyes unit, Chapter 4.) 

It will be noticed that the effluent line leading out 
of the rectifier contains an orifice and a heat inter¬ 
changer for the liquid oxygen being drawn from the 
float chamber B. The purpose of the orifice is to 
bring about a slightly increased pressure of the liquid 
oxygen in the boiler relative to the pressure of the 
effluent. By proper adjustment of the orifice dimen¬ 
sions it is possible to compensate for the resistance 
to flow of the liquid in the line, and also the resist¬ 
ance due to the operation of the inlet valve to the 
liquid oxygen cylinder of the pump. This is a matter 
of great convenience in perfecting the details of load¬ 
ing the cylinder at the inlet stroke. The further pur¬ 
pose of causing this effluent to pass through the case 
containing the oxygen injector is to prevent gas lock. 
With a pressure in the still of some 10 psi, a poten¬ 
tial loading pressure of approximately 16 psi can be 
secured through the lowering of temperature of the 
injector cylinder and piston. Of course the increased 
temperature of the effluent brought about by the 
cooling of the liquid has the effect of slightly increas¬ 
ing the heat input to the boiler. 

The dimensions of the pump have been adjusted 
to inject 35 lb of liquefied oxygen per hr up to 
1,800 psi, with operation at a theoretical rate of 32 
strokes per min. The control of the pump is through 
regulation of the time of exhaust of air from the 
driving member, and this valve also acts as a com¬ 
plete shutoff for the pump. The valve, as presently 
constructed, permits pump operation from 1 stroke 
per min to about 100 strokes per min. However, 




116 


OXYGEN COMPRESSORS AND LIQUID OXYGEN PUMPS 


the maximum quantity of liquid oxygen which the 
pump will handle depends upon the degree of per¬ 
fection and control of the loading of the cylinder. 
The pump has been operated up to 250 strokes per 
min. If satisfactory loading characteristics could be 
maintained at this rate of operation, some 200 lb of 
liquid oxygen per hr might he injected. 6 


HAND-OPERATED 
LIQUID OXYGEN PUMP 


This apparatus was designed to provide a means 
of charging high-pressure (2,000 psi) oxygen cylin¬ 
ders from a source of liquid oxygen at atmospheric 
pressure. The apparatus is hand-operated and its 
heat requirements are supplied by the surrounding 
atmosphere. 1 2 3 4 5 6 

Liquid is compressed by a piston from atmospheric 
pressure to that required and is then led through an 
air-warmed vaporizer in which it is converted to 
compressed gaseous oxygen. The compressed gas is 
led through a gauge connection into the cylinder to 
be charged. By compressing liquid instead of gaseous 
oxygen, the work necessary for the operation is min¬ 
imized. 

The finished apparatus conformed to the follow¬ 
ing specifications: 


1. Weight (empty) 140 lb 

2. Height 33 in. 

3. Space required 16x50 in. 

4. Container capacity 21.5 lb 

5. Pumping rate 10 scfm (average) 

6. Losses 

a. Loss on filling (warm), 4.0 lb 

b. Loss on standing, 0.6 lb per hr 

c. Loss on pumping one filling of oxygen (200 

cu ft delivery), 3 lb 

d. Limiting overall oxygen efficiency, 85% 


The apparatus shown in Figure 22 and Figure 23 
includes a vacuum vessel (Figure 23) provided with 
a filler port and a vent. In this vessel is a nitralloy 
cylinder with a close-fitting piston of the same mate¬ 
rial, which is actuated by the handle. The cylinder 



Figure 22. Hand-operated liquid oxygen pump. 

is fitted with a hall check valve to prevent backflow 
of oxygen. The vaporizer is mounted on the pump 
frame in such a way as to allow free convection of 
air. The oxygen outlet is provided with a gauge by 
means of which the cylinder pressure is read. 










HAND-OPERATED LIQUID OXYGEN PUMP 


117 




Lbase 


Figure 23. Hand-operated pump and vaporizer. 








































































































Chapter 7 

HEAT EXCHANGE 

By J. H. Rushton 


71 COOLING ATMOSPHERIC AIR 
TO LOW TEMPERATURES 

ne of the most important pieces of equipment 
in any air liquefaction process is the heat ex¬ 
changer. Regardless of the pressure under which the 
system operates or the type of refrigeration used, it 
is necessary to conserve such refrigeration in order 
to make the liquefaction of air economical or even 
possible. Two types of cycles, the low-pressure and 
the high-pressure, were considered for oxygen pro¬ 
duction for both the mobile oxygen units and the 
large liquid submarine units. It was necessary to 
produce the most compact heat exchanger consistent 
with the minimum pressure drop for the purpose of 
recovering the maximum amount of refrigeration 
from the effluent gases to the incoming air. A large 
part of the refrigeration load of an oxygen-producing 
unit can be wasted by large temperature differences 
at the warm end of the exchanger system. Most de¬ 
signs required temperature approaches at the warm 
end of the order of 4 to 6 F. 

High-pressure heat exchangers of efficient design 
had been rather common in the industry and in ex¬ 
perimental laboratories, but efficient and compact heat 
exchangers for low-pressure liquefaction units were 
not so well developed. Accordingly, a considerable 
amount of effort was expended to develop compact 
low-pressure heat exchangers. 

The problem of the design of mobile oxygen plants 
for the Armed Forces led immediately to the thought 
that low-pressure plants were particularly suitable for 
the purpose. 0 Because of the low operating pressure, 
the heat exchangers themselves may be used to re¬ 
move water and carbon dioxide from the air going 
to the fractionating equipment. Thus, there may be 
eliminated the usual bulky and heavy air dryers and 
carbon dioxide absorbers, freeing the unit of chemical 
supply problems. Another advantage of a low-pres¬ 
sure system is that the power requirement, and there¬ 
for the size of the driver engine and necessary gaso¬ 
line supply, is at a minimum. Low operating pres¬ 
sures also make possible the use of rotary compres¬ 
sors and expanders with a consequent saving in 
weight and size of equipment. 


Important elimination of a continuous supply of 
alumina or silica and caustic soda or potash is 
achieved by removing water and carbon dioxide from 
the refrigerated air in the main exchanger. This is 
accomplished by alternating periodically the flows 
between the two passages. A half-cycle time of three 
minutes is usual 6 and in this way, while air is being 
cooled during one half of the cycle, water and carbon 
dioxide are condensed out of the air and accumulated 
on the exchanger surface. Before the accumulation 
has become large enough to cause plugging of the 
exchanger, the two streams are interchanged and 
low-pressure nitrogen flows over the accumulated 
deposits and evaporates them while the air deposits 
its impurities in either another exchanger or on the 
other side of the heat exchanger surface. The evapo¬ 
ration is influenced by two factors: the pressure 
differential between the two streams, which aids 
evaporation; and the temperature differential, which 
hinders it. Continued operation of such exchangers, 
and the removal of condensable impurities, are only 
possible when these two factors are in proper bal¬ 
ance. 

The oldest and most successful exchanger operat¬ 
ing in this manner is the regenerator system used 
in the Linde-Frankl plant. 6 In this case there are 
two sets of regenerators, which are cylindrical ves¬ 
sels filled with disks of crimped aluminum ribbon 
coiled tightly in the form of a spiral. High-pressure 
air flows through two vessels, while low-pressure 
nitrogen and the oxygen product flow through the 
other two, the flows being reversed periodically from 
one set of regenerators to the other. The transfer 
of heat between the two streams depends upon the 
storage of heat or refrigeration in the metal packing 
during each phase of the cycle. The two gases are 
never in direct thermal contact across a metal surface. 
The cycle time in regenerators affects the heat trans¬ 
fer efficiency, as well as the thickness of the deposits 
formed and laid down during each phase of the 
cycle. 

Regenerators of this type have been used in the 
Linde-Frankl plants in Germany where long-time 
operation is desired. However, as there were little 
or no design data available on this type of equipment, 



118 


COOLING ATMOSPHERIC AIR TO LOW TEMPERATURES 


119 


a study for the determination of regenerator per¬ 
formance was carried out. 8 - 9 Before the data from 
the research were available it was necessary to set 
the size of such equipment for the first mobile unit, 
known as M-2. The results obtained later indicated 
that it would be advisable to increase the size of these 
units, and this was done by adding another section 
to each unit. 

1 he main differences between the regenerators set 
for the M-2 unit and the Linde-Frankl ones lay in 
three points: 

1. The M-2 regenerators were smaller than any 
of those known to have been built. 

2. The M-2 regenerators were designed for a 
greater temperature difference at the warm end, in 
order to decrease weight and size. 

3. The M-2 system did not use a small percentage 
of purified high-pressure air which gave the unbal¬ 
anced flow used in the Linde-Frankl plants. 

Collins had devised a low-pressure heat exchanger 
for a small oxygen unit (see Chapter 3) which 
showed great promise of providing the desired type. 
The Collins exchanger 2 - 3 ’ 6 - 10 consists of annular sec¬ 
tions filled with spirally wound ribbon. This is il¬ 
lustrated in Figure 1. In addition to its excellence 
as a heat-exchanger device, this machine was also 
capable of operating as an air purifier by removing 
water and carbon dioxide and light hydrocarbons 
by condensing them in the stream of incoming air. 
These impurities could then be evaporated when 
effluent gas streams were passed countercurrently 
through the same passages, and thus the exchanger 
could he used in a reversing fashion; these exchang¬ 
ers are normally referred to as reversing heat ex¬ 
changers. 

Reversing exchangers consisting of these Collins 
tubes are characterized by a high rate of heat trans¬ 
fer and a small total surface, as compared with re¬ 
generators which operate with low heat transfer rates 
and large surfaces. The thermal efficiency of a Col¬ 
lins tube exchanger is less affected by cycle time than 
are regenerators because there is essentially no stor¬ 
age of heat in the metal. 

The condition that each passage of a regenerator 
or reversing exchanger he capable of carrying the 
low-pressure gas with a reasonably low-pressure drop 
requires that both passages be rather large. For this 
reason this type of exchanger is limited to low pres¬ 
sures because, as the pressure goes up, the loss of 
compressed air on reversal finally becomes prohibi¬ 
tive. Construction is also heavy, as advantage can¬ 


not be taken of the fact that the high-pressure air 
stream could be carried in relatively small conduits, 
due to the allowable pressure drop. 

Other extended surface exchangers were used for 
various applications and will be referred to in due 
course. 

High-pressure exchangers, for the most part, have 
been designed using suitable tubing both in parallel 
straight passes and spirally wound passes. One of 
the most successful high-pressure exchangers was 
that incorporated in the Giauque unit (Chapter 4), 
and which is referred to as the Giauque-Hampson 
exchanger. 14 - 15 This exchanger is illustrated in Fig¬ 
ure 9. The Giauque-Hampson type exchanger was 
also used to purify incoming air by means of re¬ 
frigeration. However, when acting as purifiers, these 
exchangers were allowed to have impurities depos¬ 
ited and, before any serious pressure drop or block¬ 
ing occurred, were then switched out of the line and 
thawed to such a temperature that the impurities 
could he drawn off as liquid or blown out as vapor. 
Heat exchangers used in this fashion are referred 
to as switch exchangers. 

Although the first small mobile unit M-2 was 
built with Frankl-type regenerators, 1 the results ob¬ 
tained by Collins indicated that a saving in weight, 
volume, and loss of high-pressure air could be ob¬ 
tained by the substitution of reversing exchangers for 
the regenerators. Since the oxygen produced had to 
he highly compressed before use, it had to be free of 
oil and, therefore, could not be warmed in a regenera¬ 
tor which had previously been contaminated by air 
carrying oil. The Collins tube, on the other hand, 
can be built with a third annulus or tube in thermal 
contact with the two annuli which carry air and 
nitrogen alternately. This can be used to carry the 
oxygen stream continuously. Thus, since the oxygen¬ 
warming surface is never in direct contact with air, 
the oxygen discharged from Collins tubes will be 
free of oil and very dry. Again, due to the smaller 
size, there is less loss of high-pressure air on re¬ 
versal and depressuring with the Collins tube ex¬ 
changers. As the original l^g-in. OD tube designed 
and tested by Collins was small, and thus required 
a large number to be used in parallel in a unit to 
produce 1,000 cfh of oxygen, a larger-diameter tube 
was developed. Such a section of 3^-in. OD was 
built and tested for heat transfer with excellent re¬ 
sults. Consequently, when the M-2 unit on the first 
run failed to produce liquid, due to poor insulation 
and excessive heat leak, it appeared advantageous 




120 


HEAT EXCHANGE 


to switch to the larger tubes on this unit, later to be 
called M-2R, as well as on the M-7, or single-trailer 
unit. The latter was made possible by the great re¬ 
duction in space requirement obtained by the use 
of the Collins exchangers. 

In the Linde-Frankl plant, as mentioned above, 
a small portion of the air taken into the plant is dried 
and freed of carbon dioxide, and is used to unbalance 
the flows in the regenerators, making the low-pres¬ 
sure stream somewhat larger than the high-pressure 
stream. This has been reported to be necessary in 
order to insure complete removal of impurities from 
the regenerators over a long period of time. Early 
tests made with reversing exchangers by Collins in¬ 
dicated, however, that successful operation was pos¬ 
sible with balanced flow, and that reversing exchang¬ 
ers differed from regenerators sufficiently to make 
unbalancing and consequent purification of a portion 
of the air unnecessary. The reversing exchangers 
in the mobile units were designed to operate with 
balanced flows which resulted in the simplification 
of equipment desirable in a mobile unit. 

7 2 HEAT EXCHANGER FOR LOW- 
PRESSURE OPERATIONS 

The use of Collins exchangers in air liquefaction 
plants is a recent development which promised to 
be of considerable importance. These exchangers 
are essentially concentric tubes joined by a coiled rib¬ 
bon packing metallically bonded to the tubes. They 
were successfully applied by NDRC contractors to 
both small and large units for the production of gas¬ 
eous oxygen by liquid air fractionation. The Collins 
unit has a capacity of 150 scfh (standard conditions 
of 60 F and 1 atm) at 99.5% purity; the units known 
as M-2R and M-7 each have a capacity of 1,200 scfh 
oxygen at 99.5%; M-3 has a capacity of 325 scfh 
at the same purity, and M-5 a capacity equivalent 
to 400 lb liquid oxygen per hr. The Collins unit 
operates at a head pressure of 150 psi, while the 
latter four units operate on an air pressure of 105 
psia. 

The Collins type exchangers serve a two-fold pur¬ 
pose, namely, recovery of refrigeration, and removal 
of condensable impurities such as water and carbon 
dioxide. 1,6 To effect removal of impurities the inlet 
high-pressure air and the returning nitrogen-rich 
waste gas alternate with each other in flowing 
through their two-heat transfer channels, each gas 
always flowing in the same direction through either 


channel. The impurities deposited by the high-pres¬ 
sure air are picked up after “reversal” by the waste 
gas and carried back to the atmosphere. Reversals 
occur at frequent intervals and are automatically 
controlled. 

7 -3 HEAT TRANSFER RATES IN 
COLLINS EXCHANGER 
PACKING 

This section presents a correlation of heat trans¬ 
fer data in Collins exchanger tubes, which has served 
as a satisfactory design criterion. 5 The recommended 
correlation applies to all the various types of Collins 
packing used in the program. 

Data on the 1^-in. OD double-annulus tube were 
obtained by Collins of the Massachusetts Institute 
of Technology before March 1942, 10 and on the 
3%-in. OD double-annulus tube by Dodge of Yale 
University in 1942. 9 

The exchangers are concentric tubes with coiled 
ribbon packing in the space between tubes. This 
packing is made by winding a copper ribbon on edge 
on a mandrel and then stretching the tightly wound 
coil to form a helix of desired pitch. The coil is 
wound upon the smaller of the two tubes bounding 
the annular space, and adjacent turns are separated 
by solder wire. The outer tube is slipped over the 
packing; good mechanical contact between packing 
and both tubes is made either by expanding the inner 
tube or contracting the outer, and the assembly is 
heated to form a solder joint between the packing 
and the tubes. 

Figure 1 shows the dimensions of the tubes and 
packing used in the test exchangers. The l^-in. 
OD exchanger has a 7-ft effective length; the other, 
19.5 in. 

The exchanger tube tested at MIT was 

suspended in a chamber evacuated by a diffusion 
pump. To reduce radiation the exchanger was 
wrapped with aluminum foil. The nitrogen or helium 
gas circulating in a closed system entered the inner 
annulus at approximately 90 psia and room tempera¬ 
ture. Gas leaving the other end of the exchanger 
was throttled to about 20 psia, cooled against liquid 
nitrogen, and returned through the outer annulus. 
A bleeder line was installed between the exchanger 
and the throttle valve. 

Tests on the 3%-in. OD exchanger were con¬ 
ducted at Yale. Compressed air at room tempera¬ 
ture passed through the outer annulus, was heated 



HEAT TRANSFER RATES IN COLLINS EXCHANGER PACKING 


121 




COLLINS ANNULAR PACKING 

Figure 1. Collins exchanger tube details. 



MATERIAL « TUBES - BRASS 

PACKING - COPPER 


to approximately 200 F in a steam heater, and re¬ 
turned through the inner annulus. Before being re¬ 
leased to the atmosphere the air flowed through a 
displacement-type gas meter. The four terminal 
temperatures were measured by copper-constantan 
couples. The tube and the headers were insulated 
with magnesia. 

The following equation correlates the perform¬ 
ance : 


hfDe 

k 


0.114 


DcG y 7 ^ c p u y* 


( 1 ) 


h f = fluid film coefficient, applied to entire wetted 
surface, Btu hr -1 ft -2 F -1 . 

D c = equivalent diameter, feet, and is defined as 
4 S/b where 5 = volume occupied by fluid 
per ft of tube length, ft 3 per ft, and b = total 
wetted surface (tube plus ribbon) per ft of 
tube length, ft 2 per ft. 


G = mass velocity of fluid, lb hr -1 ft -2 = W/S. 
W = rate of fluid flow, lb per hr. 
k — thermal conductivity of fluid, Btu hr -1 ft -2 
(F per ft) -1 . 

a = viscosity of fluid, lb hr -1 ft -1 = 2.42 X cen- 
tipoises. 

C p = specific heat of fluid at constant pressure, 
Btu/lb. 

This equation fits the data with an average devia¬ 
tion of 2.5% and a maximum of 5.8%. 

The sixteen test runs cover the following range of 
variables: 

hf 26.8 to 90.3 
D e 0.00722 to 0.00999 
H 0.327 to 0.0491 
k 0.0106 to 0.0718 
DcG/n 393 to 6800 
Cpii/k 0.69 to 0.78 
Fluids air, nitrogen, helium 






































122 


HEAT EXCHANGE 



Figure 2. Plot of equation for heat transfer in Collins 
packing. 


Fluid properties should be evaluated at mean fluid 
temperature. To calculate the overall coefficient Lb- 
based on any reference surface b r , the following gen¬ 
eral equations are used: 

h = (i + F )i + Or + Fi )t~ + k k' (2) 

hf — hf X fin efficiency (3) 

where U r = overall coefficient based on surface b r , 
Btu hr -1 ft -2 F _1 . 

b r = arbitrary reference surface, ft 2 per foot 
of exchanger length. 

F = fouling resistance, Btu" 1 hr ft 2 F, cor¬ 
rected for fin efficiency. 
t w = thickness of wall between the two 
fluids, ft. 

k w = conductivity of wall material, Btu hr -1 
ft' 2 (F per ft) -1 . 

b w = mean of inner and outer wall surfaces, 
ft 2 per ft of exchanger length. 

Subscripts 1 and 2 refer to the two fluids between 
which heat is being exchanged. 

The fin efficiency may be approximated by assum¬ 
ing that the fins are straight bars of uniform cross 
section extending from the wall. 5 ’ 15 

When the value of U r is known the exchanger per¬ 
formance is determined from the equation: 

Q = U r A, AT, (4) 



Figure 3. Fin effectiveness of Collins exchanger pack¬ 
ing. 


where Q is the heat transferred, Btu per hr, AT is 
the mean temperature difference between the two 
fluids, F, and A r is the reference area, sq ft, calcu¬ 
lated as the product of b r and the effective length of 
tube in the exchanger. 

7 4 RECTANGULAR MULTIPIN 
HEAT EXCHANGER 

The reversing heat exchangers prove to be very 
successful both for heat exchange and air purifica¬ 
tion. 15 However, their configuration was such that 
it was necessary to manifold a number of tubes in 
parallel even for small-sized plants. The large M-5 
liquid oxygen unit (see Chapter 3) had originally 
been laid out using regenerators and one of the 
original requirements for the plant was that it need 
operate continuously for a period of only 10 to 12 hr 
at low-temperature producing conditions. After the 
successful temperatures of the reversing heat ex¬ 
changer technique, it was felt desirable to re-engineer 
the M-5 unit so as to make it capable of operating 
continuously for days or weeks at a time, if desired. 
The regenerator system originally installed was not 
capable of such continuous operation. A large-sized 
assembly was laid out on the basis of using Collins 
tubes (60 in parallel) for the heat exchanger system 
in the M-5 unit, and these tubes have operated suc¬ 
cessfully. However, it had long been felt that there 
could be a considerable saving both in expense of 











RECTANGULAR MULTIPIN HEAT EXCHANGER 


123 


fabrication of Collins heat exchangers and in space 
and heat insulation losses if an exchanger could be 
devised which would allow larger individual flow 
passes for the gases. Such an exchanger was finally 
built in size sufficient for a 1,000 cfh gaseous oxygen 
unit. This exchanger was then the equivalent of the 
exchanger system in the M-7 units. The actual cross- 
section area for the same performance as for the 
Collins tubes was between 40 to 50% of that required 
for the Collins tubes. Manifolding was considerably 
simplified in this exchanger which is shown in Fig¬ 
ure 4. The final design of the exchanger has been 
named “Multipin ' (Figure 5), and is so referred to 
in reports. 15 


the rectangle contacting the channel plates are cov¬ 
ered with solder so that each exchanger passage 
becomes in effect two parallel plates connected by a 
multitude of straight pins. 

Basic dimensions of the packing and exchanger 
are listed below. 


Wire diameter 0.032 in. 

Packing 0.760 in. 

Pins per square inch packing 248 

Solder sheet at contact surface, thickness 0.020 in. 
Copper passage plates, thickness 0.043 in. 

Exchanger passage, width 20.0 

Exchanger passage, length 11 ft 6 in. 


The exchanger was built in two sections in series, 
one 6 ft and the other 5 ft 6 in. long with the shorter 



The exchangers are parallel plates with a rectangu¬ 
lar coil-wire packing in between them. The packing 
is made by winding copper wire in the form of a 
rectangular helix of desired pitch, height and width. 
Helices are wound right- and left-handed alternately 
in order that they may mesh together. The meshed 
helices form the packing which is placed between 
solder sheets and then between copper plates to form 
the separate channels of the exchanger. The assem¬ 
bly is heated to form a solder bond between the 
packing and the plates. In this process the ends of 


.0432" 



length at the colder section of the exchanger. The 
warm section of the exchanger thus contained 5 
passages and the cold section was built with 6 pas¬ 
sages. Exchanger details are shown in Figure 5. 

The Multipin exchanger occupies 1.46 cu ft, or 
slightly less than half the volume of a Collins tube 
assembly. Actually the comparison is even somewhat 
more in favor of the Multipin exchanger because the 

































































124 


HEAT EXCHANGE 


controlling pressure drop through the Collins assem¬ 
bly would be approximately 4.5 psi as against a 
pressure drop of some 3 psi for the former exchanger. 
A Collins exchanger, to do the same heat transfer 
duty at the same pressure drop found for the Multipin 
exchanger, would have to be somewhat larger than 
estimated in the preceding paragraph, and increase 
further the volumetric saving afforded by the Mul¬ 
tipin assembly. 

A clear comparison between the characteristics of 
the two exchangers required to perform the duty 
being discussed can be obtained from the following 
table. 15 

Effective Pressure 

Exchanger Volume, ft 3 Area, ft 2 Drop, psi 
Multipin 1.46 378 3.0 

Collins 3.06 470 4.5 


Another advantage of the Multipin construction 
lies in the relatively easier manifolding problem, with 
consequent reduction in volume of manifold piping 
required per volume of exchanger. 

It is interesting to note that the gas film coefficient 
can be predicted and good agreement made with the 
experimental results obtained through the use of a 
simplified dimensional equation for gases flowing 
normal to staggered tubes. This equation is 

h = 0.mc p G^ x Dy (5) 

where G max —W/S 

D 0 = outside tube diameter, ft. 


Application of this equation directly to this case 
results in a value of h = 62.3 which is twice the 
figure observed. This is at least partly explainable 
since the Multipin exchanger utilizes pins which are 
soldered to the passage walls and this wall effect is 
not considered in the above equation. 

However, if the above equation is modified for the 
present conditions by substituting D e for the pin 
diameter and thus basing the coefficient on total 
washed surface the predicted coefficient is, 

h = (0-^)(0.24)(182) = 

(0.1575) 


The observed coefficient, corrected for fin effi¬ 
ciency is 


h 


observed — 


30.2 

0.823 


= 36.7 


The agreement is surprisingly excellent and, al¬ 
though this may be coincidence, it is worth notice in 


passing, and if more experimental data becomes 
available, warrants further investigation. 

There is strong evidence that the increased heat 
transfer performance obtained in the Multipin ex¬ 
changer is the result of added fluid turbulence in the 
packing. As indicative of the magnitude of this effect 
it is estimated that the friction factor obtaining at a 
value of modified Reynolds number of 1,500 in the 
clean exchanger is approximately 0.35. The value of 
the friction factor for the same Reynolds number in 
a Collins tube would average 0.13, although this 
figure might be as high as 0.15 for certain samples. 

The equation (1) for predicting the heat transfer 
coefficients in Collins tubes has been applied to the 
Multipin exchanger and found to be very conserva¬ 
tive. The experimental data available indicate a value 
of h approximately 75% greater than that predicted 
by the present equation. Since the experimental 
data are very meager it is recommended that the 
equation for Collins tubes be retained in form for the 
Multipin exchanger with a 50% increase in the con¬ 
stant of the equation. This equation then becomes 


hfD e 


K 


= 0.175 


DeG \°- 7 C/il 1/3 

(K) 


( 7 ) 


It is further suggested that the simplified dimen¬ 
sional equation 

0.133c o C°- 6 


h f = 


D e 0i 


( 8 ) 


is equally applicable to this type of exchanger and 
should be checked if further experimental results 
become available. 

A large-sized heat exchanger based upon this rec¬ 
tangular and multiple principle has been designed for 
incorporation in the M-5 liquid oxygen plant. 15 This 
work was carried on by the University of Pennsyl¬ 
vania Thermodynamics Research Laboratory under 
contract NObs-2477, and the continuation of this 
development can be followed by reference to reports 
from that laboratory under the Navy contract. 


7 5 LIQUEFIER AND SUBCOOLER 

A special exchanger sample was submitted by the 
Trane Company and its heat transfer and pressure 
drop characteristics determined in tests conducted at 
the Central Engineering Laboratory. This type of 
exchanger is to be used for the new liquefier and sub¬ 
cooler for units of the M-5 and M-6 type. 6 ’ 15 









LIQUEFIER AND SUBCOOLER 


125 


The exchanger is a double-annulus packed tube 
5 in. OD x 4 ft effective length, in which the annuli 
are packed with 0.013 in. thick corrugated sheet 
forming longitudinal fins about y& in. apart and 0.680 
in. high. The total wetted surface in the outer an¬ 
nulus is 50.9 sq ft and in the inner annulus 33.8 sq ft. 
Exchanger details are shown in Figure 6; Figure 7 
shows the header construction. 


McAdams. Because of unexplained discrepancies in 
temperature measurements the test results were cal¬ 
culated in two ways. Terminal temperatures were 
first taken as the average between glass thermometer 
and thermocouple readings, and then from the glass 
thermometer readings alone. The experimental re¬ 
sults are shown as crosses. The experimental points 
fall well below the predicted values. The curve 


SC ALE-3"= l" 



The exchanger was tested with air flowing through 
the inner annulus, then through a heater, and re¬ 
turning through the outer annulus. The air flow rate, 
terminal temperatures and pressures were measured. 
Additional pressure taps at the packing boundaries 
in the outer annulus permitted study of the pressure 
drop in the headers. The experimental data are sum¬ 
marized and the results plotted in Figure 8. 

Predicted values of film coefficient were obtained 
using the Dittus-Boelter equation with D taken as 
the hydraulic diameter. Correction for fin efficiency 
was then made for each annulus using the method of 


through the experimental points is obtained by in¬ 
cluding a fin contact resistance in addition to the 
fin efficiency already considered. The value of this 
contact conductance (inverse resistance) required to 
correlate the experimental data is 320 Btu per hr 
per sq ft per F. This is a total figure for both annuli 
and is based on the 3.5 in. tube surface. 

Pressure drop characteristics were treated very 
briefly for the outer annulus only, since no header 
pressure drop correction was available for the inner 
annulus. The friction factor was found to be some 
30 to 40% higher than predicted by standard methods. 






















































126 


HEAT EXCHANGE 


T CST PRESSURE 35 PSl 

MOTES: SOTT SOLDER ALL JOINTS TO EXCHANGER TUBE 
SILVER BRAZE ALL OTHER JOINTS 

WALL THICKNESS OF ALL TUBING TO BE ABOUT 0.065 IN. 



Figure 7. Trane exchanger header details. 


76 HIGH-PRESSURE HEAT 

EXCHANGERS 

The use of Hampson-type exchangers in gas lique¬ 
faction plants has long been practiced. This type of 
heat exchanger, first devised by Hampson, consists 
of coils of small high-pressure tubing wound spirally 
within a cylindrical shell. In general, the entering 
high-pressure process gas is carried in the coils, 
which are washed by cold low-pressure waste gas. 
This form of exchanger is very efficient and com¬ 
pact, and has been successfully used in this program 
in several small units for the production of oxygen 
by liquefaction and fractionation of air. 

Although in general use for many years, no data 
were available for the accurate design of such ex¬ 
changers until the results of W. F. Giauque’s experi¬ 
ments at the University of California were obtained. 14 
The exchangers were built and studied by Giauque 
in connection with the development of a liquid oxygen 
generator, and are essentially modified Hampson 
exchangers consisting of tubing wound in helical 
layers within a cylindrical shell. The tubes are built 



Figure 8. Heat transfer correlations for Trane ex¬ 
changer. 


up layer by layer with alternate layers wound left 
and right. By selecting the proper number of tubes 
to be wound in parallel in a given layer, or by ar¬ 
ranging crossovers between layers, all the tubes in 
parallel can be made of equal length. This basic de¬ 
sign is used with various tube sizes and spacings to 
meet a variety of exchanger requirements. A de¬ 
tailed discussion of construction as well as test data 
is presented in a final report. 14 

7 7 HEAT TRANSFER COEFFICIENTS 
FOR HIGH-PRESSURE AIR 
INSIDE TUBES 

Data on the individual heat transfer coefficients 
for high-pressure gas in small tubes were not avail¬ 
able prior to the work of Giauque. The experimental 
results were correlated by Giauque through the use 
of a modified dimensional equation used for low- 
pressure gases flowing inside tubes. However, it 
seemed desirable to correlate the results more gen¬ 
erally by the use of a proven dimensionless equation 
and in this way, if possible, extend the application 
of a standard and common method of predicting the 
heat transfer coefficient to this case. 

Four copper tubes 0.250-in. OD (0.035-in. wall) 
were soldered together in parallel for a length of 40.5 
ft to form the exchanger, two tubes being used for 
each passage. 14 Terminal temperatures and pressures 
were measured in a series of four experiments at 
























































COEFFICIENTS FOR HIGH-PRESSURE AIR 


127 


various elevated pressures in which air was taken 
through two of the tubes, passed through a cooler and 
then passed counter-current through the two remain¬ 
ing tubes. The exchanger was made in the form of a 
loose coil about 20 in. in diameter and well insulated. 
Calculations were made for each third of the ex¬ 
changer length, and heat leak and metal resistance 
were assumed to be negligible. The air flow was 
1.43 X 10° lb per hr per sq ft and a summary of 
calculated results is given in Table 1. 


Table 1. Summary of experimental results. Individ¬ 
ual heat transfer coefficients for high-pressure air 
inside H hi. tubing. 


Run No. 

Average 

pressure 

(psia) 

Average temp. 
(F) 

h, heat transfer 
coeff Btu/(hr) 
(sq ft) (F) 

la 

3,260 

+ 12.5 

813 

2a 

2,420 

+ 9.0 

801 

3a 

1,540 

+ 6.9 

711 

4a 

3,550 

+ 15.9 

788 

lb 

3,260 

- 50.0 

864 

2b 

2,420 

- 54.0 

822 

3b 

1,540 

- 56.7 

762 

4b 

3,550 

- 47.6 

826 

lc 

3,260 

-103. 

997 

2c 

2,420 

-105. 

975 

3c 

1,540 

-110. 

926 

4c 

3,550 

-103. 

940 


Correlations. The results of Table 1 were cor¬ 
related by Giauque using a modification of the simpli¬ 
fied dimensional equation 

h — 0.0144c p G°- 8 Z) _0 - 2 , 
where li = Btu/(hr) (sq ft) (°F), 

c p = specific heat, fluid, Btu/(lb)(°F), (9) 

G = fluid flow, lb/(hr) (sq ft), 

D = ID tube, ft. 


The correlation was satisfactory when the constant 
of equation (9) was reduced to 0.0120, the equation 
becoming: 

h = 0.0\20c p G°- 8 D- 0 - 2 . (10) 


It is not surprising that the constant of equation 
(9) was found inapplicable since this equation is a 
simplified form of the general Dittus-Boelter ex¬ 
pression 


UP 

k 


0.023 




( 11 ) 


where all terms are the same as previously defined 
with the addition of: 


k = thermal conductivity of fluid 
Btu/(hr) (sq ft) (F per ft) 
fi = fluid viscosity, lb/(hr) (ft) 


Equation (9) is derived from expression (11) by 
inserting average values of: 

= 0.78 

k 

and /n = 0.0435 

Since the values assigned above do not hold at the 
extreme temperatures and pressures existing at the 
conditions of test, it is easy to understand the need 
for an adjusted constant to correlate the experimental 
results by means of simplified equation. 

It was felt that in light of the deviation of the test 
results from equation (9), it might he better to cor¬ 
relate the data using the dimensionless Dittus-Boelter 
relation to compensate for the variation in the thermal 
properties of the fluid over the temperature and pres¬ 
sure ranges covered. The only drawback to this 
approach is the necessity for extrapolating existing 
data for the fluid properties to evaluate these proper¬ 
ties at the experimental conditions. However, the 
extrapolation was not too difficult and it was felt 
that such an estimate was superior to the assumption 
that the physical properties of air remained constant 
over the range of interest. 

A summary of the heat transfer coefficients pre¬ 
dicted by the Dittus-Boelter equation for the condi¬ 
tions existing in the 12 experimental runs reported 
in Table 1 is given in Table 2. The physical proper¬ 
ties of air were all taken from the Data book, Report 
OSRD Number 4206, with the exception that values 
of c v not included in this report were taken from the 
data of Williams. 11 Values of viscosity and the group 
Cpfi/k are tabulated to indicate the extent of the devia¬ 
tions in these values from the average figures as¬ 
sumed in equation (9). 

F. G. Keyes 11 has also analyzed the data of 
Giauque using the Dittus-Boelter equation and some¬ 
what different relations for determining air proper¬ 
ties. The calculations of Giauque and Spector 15 are 
compared with the observed experimental results in 
Table 3. 

Heat Transfer in Coils. Consideration of the effect 
upon the heat transfer coefficient resulting from the 
use of high-pressure tubes wound in helical layers led 
to the investigation of the individual heat transfer 
coefficients in % 6 -in. tubing coiled in a spiral of very 
small diameter. Experimental procedure similar to 
that described in the previous section was adopted 
using an exchanger wound in a spiral -y^-in. ID. For 
this severe case the value of the heat transfer coeffi- 











128 


HEAT EXCHANGE 


cient was found to be increased approximately 30% 
of that for larger diameter coils. Since the diameter 
of the coils used in most Hampson-type exchangers 
is considerably larger than the test spiral, it is esti¬ 
mated that the increase in heat transfer coefficient due 
to coiling, is very small for the cases of interest. 

Recommendations. 15 In order to avoid the neces¬ 
sity for using special correlations in the design of 
Giauque-Hampson exchangers it is recommended 
that the value of the heat transfer coefficient inside 
the tubes be calculated from the Dittus-Boelter rela¬ 
tion, equation (11). 


those predicted by the Dittus-Boelter relation is ex¬ 
cellent until an average operating temperature in the 
neighborhood of —100 F is reached, where the use 
of this equation results in values which are conserva¬ 
tive by as much as 15 to 25%. Since the air proper¬ 
ties used at this temperature have been estimated by 
extrapolation of unknown quality, it is suggested 
that the use of more accurate physical data might 
result in better agreement for such cases; and it is 
recommended that this point be checked if and when 
more accurate data on the physical properties of air 
become available. 


Table 2. Predicted heat transfer coefficients for high-pressure air inside j4-in. tubing. Dittus-Boelter equation. 


Run No. 

Pressure psia 

Temp. F 

Viscosity 
lb/(hr) (ft) 

Cpt/k 

dimensionless 

h, Btu/(hr) 

(sq ft) (F) 

la 

3,260 

+ 12.5 

0.0590 

1.03 

821 

2a 

2,420 

+ 9.0 

0.0542 

1.01 

805 

3a 

1.540 

-P 6.9 

0.0490 

0.95 

765 

4a 

3,550 

+ 15.9 

0.0600 

1.05 

825 

lb 

3,260 

- 50.0 

0.0546 

1.16 

910 

2b 

2,420 

- 54.0 

0.0499 

1.12 

804 

3b 

1,540 

— 56.7 

0.0450 

1.06 

760 

4b 

3,550 

- 47.6 

0.0579 

1.21 

830 

lc 

3,260 

-103 

0.0508 

1.32 

862 

2c 

2,420 

-105 

0.0474 

1.43 

830 

3c 

1,540 

-110 

0.0410 

1.39 

700 

4c 

3,550 

-103 

0.0523 

1.29 

852 



Table 3. Heat transfer coefficients for high-pressure air 

inside small tubes. 




h, Btu/(hr) (sq ft) (F) 


% Deviation 







Run No. 

Giauque eq (9) 

Keyes eq (11) 

Spector Table 2 

Giauque observed 

tions from 






observed 

la 

803 

820 

821 

813 

1.0 

2a 

790 

815 

805 

801 

0.5 

3a 

734 

775 

765 

711 

7.6 

4a 

815 

767 

825 

788 

4.2 

lb 

898 

850 

910 

864 

5.3 

2b 

863 

844 

804 

822 

7 7 

3b 

801 

805 

760 

762 

0.3 

4b 

900 

955 

830 

826 

0.5 

lc 

1,020 

931 

862 

997 

13.5 

2c 

1.056 

917 

830 

975 

14.7 

3c 

1,020 

869 

700 

926 

24.3 

4c 

996 

932 

852 

940 

9.4 


This equation has been shown to check the results 
of Giauque’s experimental work with sufficient ac¬ 
curacy for design purposes. This is especially true 
since the resistance to heat transfer inside the tubes 
is small compared with the resistance outside the 
tubes and is therefore not too important in the over¬ 
all design of the exchanger. 

The agreement between observed coefficients and 


' 1 Heat Transfer Coefficients for 

Low-Pressure Air Outside Tubes 

The previous section indicates that the controlling 
resistance to heat transfer in a Giauque-Hampson 
exchanger (Figure 9) lies in the low-pressure gas 
film outside the coils. Thus, the intelligent design of 
such an exchanger requires that the heat transfer 
coefficient for low-pressure gas flowing past the tube 











COEFFICIENTS FOR HIGH-PRESSURE AIR 


129 


coils be capable of prediction with good accuracy. 
Furthermore, the correlation should be broad enough 
to include such variables of design as tube size, spac¬ 
ing between tubes (pitch), spacing between tube 
layers, and number of tube layers. 



Figure 9. Giauque-Hampson interchangers, RLHL-3 
(left) and RLHL-2 {right). 


Five experimental exchangers of the same general 
type but embodying variations as noted above were 
built and tested. 5 No general correlation covering 
the performance of these exchangers was developed, 
but instead it was found necessary to express the 


heat transfer characteristics of each of the exchangers 
by the use of different equations. 

Correlations. The results were correlated by 
Giauque using equations of the form, 

l, = Kc,(l±y (12) 

where K = constant. 

n rr constant. 

c p = fluid specific heat, Btu/(lb)(F). 

W — fluid flow, lb per hr. 

5" = superficial cross-sectional area of ex¬ 
changer, sq ft (total area between inside 
of exchanger shell and outside of core 
tube). 

Unfortunately this equation did not correlate all 
the data and different values of K and n were re¬ 
quired by the data for each exchanger. Values of K 
ranged from 0.45 to 1.53 while n varied from 0.60 
to 0.75. 14 

In considering a more general correlation the fol¬ 
lowing variables were noted: 

1. Tube size varied from ^ in. to Ft in-, 

2. Spacing between tubes (pitch) varied from 
0.031 to 0.096 in., 

3. Spacing between tube layers varied from 0.000 
in. to 0.053 in., 

4. Number of tube layers varied from 3 to 11. 

In taking into account these variables the correc¬ 
tion for tube size was made by a term D a where D 
is OD of the tube in feet. Investigation of the litera¬ 
ture on heat transfer to fluids outside of tubes dis¬ 
closed no effect of pitch over wide ranges of this 
variable, and hence this factor was assumed to have 
no effect. The influence of both items 3 and 4 was 
included by the use of the term G max. where G max is 
pounds per hour of gas flow per square foot of net 
free cross-sectional area. This last assumption made 
it impossible to include exchanger RLHL-1 in the 
correlation, since the net free cross-sectional area 
available for gas flow could not be calculated with any 
degree of accuracy for this sole case where the spacing 
between tube layers was zero. 

A literature survey disclosed that the value of the 
exponent a might well be taken as —0.4 and the 
value of b as 0.6 by analogy to heat transfer by fluids 
flowing outside banks of tubes. Accordingly the data 
were fitted to an equation of the form 

Ji = K'c p GV**D -'>A (13) 



























130 


HEAT EXCHANGE 


The calculations are summarized and the results 
plotted in Figure 10. The constants derived for each 


set of exchangers are : 


Exchanger 

K 

RLHL-2 

0.107 

RLHL-3 

0.102 

RLHL^t 

0.115 

RLHL-5 

0.115 


The general equation correlating all the data is 
obtained from Figure 10. 

h = 0.n0c p G™ x D- 0i . (14) 

It is significant to compare equation (14) with the 
expression for gases flowing normal to staggered 
tubes which is given for the same units as 

h = 0A33c p G OG D-°\ (15) 



Figure 10. Plot of data on Giauque-Hampson ex¬ 
changers. 


7 8 RECOMMENDATIONS FOR HIGH- 
PRESSURE HEAT EXCHANGERS 

Heat Transfer. 15 In the design of Giauque-Hamp¬ 
son exchangers it is recommended that the Dittus- 
Boelter equation be used to evaluate the heat transfer 
coefficient inside the tubes, and that the dimensional 
equations (14) and (15) apply to low-pressure gas 
flowing outside the tubes. 

Use of these equations is desirable since neither 
expression is unique for this application. The Dittus- 
Boelter equation is generally applicable in cases of 
fluid flow inside tubes, and the above correlation for 


low pressure gas outside tubes agrees within 12% 
with a similar expression found to apply for the gen¬ 
eral case of gases flowing normal to staggered tubes. 

Since it was not possible to include exchanger 
RLHL-1 in the correlation because the spacings be¬ 
tween tube layers was zero, the question naturally 
arises as to the minimum spacing between tube layers 
for which the correlation holds. It is felt that there 
is no minimum value as such, but rather that the 
limitation is imposed by the accuracy with which the 
free area can be determined for purposes of evalu¬ 
ating G max . 

The spacing between tube layers for the four ex¬ 
changers used in the correlation are the following 14 : 


Exchanger 

K 

RLHL-2 

0.036 in. 

RLHL-3 

0.018 in. 

RLHL-4 

0.052 in. 

RLHL-5 

0.033 in. 


It is probable that the correlation applies to the 
smallest spacing practically attainable in an ex¬ 
changer of this type, provided sufficient physical data 
are available on the exchanger to permit accurate 
evaluation of G m!iX . 

It would be of interest to consider the coil of this 
type exchanger as a packing and attempt a correlation 
on the basis of an equivalent diameter D e . The cor¬ 
relation might then be expressed in terms of a dimen¬ 
sionless equation of the general type. 


UP 

k 


= K" 




(16) 


where all terms are as previously defined with the 
addition of 

K" = constant of the equation. 

D r = equivalent diameter, ft rr 4 S/b. 

S' = volume occupied by fluid per foot of ex¬ 
changer length, cu ft per ft. 
b — total wetted surface per ft of exchanger 
length, sq ft per ft. 
zv = mass velocity, lb per hr. 

G = W/S' lb per (hr)(sq ft) 
x,y — exponents. 


Pressure Drop. This question can be adequately 
considered for the present by using standard friction 
factors to evaluate pressure drop inside the tubes. 
The pressure drop outside the coils can be obtained 
in the following manner. 








REGENERATORS 


131 


Giauque has presented the following relation for 
pressure drop in one of his experimental ex¬ 
changers, 13 

Pi 2 — P 2 2 = 3.8 X 10 ~ 8 Tiu 0 - 2 n(~\ 2 , (17) 

where P = pressure, psia. 

T = temperature, K 

A 7 = length of exchanger, ft. 

[x ■=. viscosity, poises. 

W — fluid flow, lb per hr. 

A = superficial cross section of exchanger, ft 2 
(as previously defined for heat transfer). 

This equation was obtained over an experimental 
range of W/S = 1,000 to 4,500 and a temperature 
range of 200-300 K and can be simplified to the 
expression 


A P G 
N 


= 1.135 X 10- 8 



(18) 


where all terms are those of equation (17) with the 
addition of 


P G = pressure drop, psia, Giauque. 
u = viscosity, centipoises. 
p = fluid density, lb per cu ft. 

Unfortunately, equation (17) is based on a super¬ 
ficial area A and is not considered generally applica¬ 
ble without modification. The ratio R of actual cross- 
sectional area filled, to superficial cross-sectional area 
for the experimental exchanger under consideration 
can be calculated as equal to 0.578, and for any other 
exchanger being considered this factor can be evalu¬ 
ated as 


4 

where D — tube OD, in. 
n — coil pitch, in. 


It is recommended that a general method of calcu¬ 
lating pressure drop outside tubes be developed for 
these exchangers. Use of an equivalent diameter D e 
for the exchanger and a modified Reynolds number 
D r G/ju where the terms are as defined for equation 
(16) might allow correlation of pressure drop char¬ 
acteristics in terms of the commonly used friction 
factors. 

7 9 OTHER HEAT EXCHANGER 
DESIGNS 

A great many novel heat exchangers have been 
proposed and built in connection with the oxygen 
program. A description of these can be found in 
reports 10 ’ 15 and from performance data reported on 
them. Modifications of common types of heat ex¬ 
changers have been used for process air in the M-7 6 ’ 15 , 
M-5 6 ’ 15 , M-6 6 ’ 15 ’ 16 and details can be obtained in these 
references. 

7 10 RADIATORS AND AIR-COOLERS 

The compressors used in the mobile oxygen units 
all required interstage and aftercooling. This was 
effected by conducting the interstage and final pres¬ 
sure air to radiators or exchangers of conventional 
type. Designs were based for the most part on manu¬ 
facturers’ data 6 although in some cases data were 
obtained in NDRC experimental work for specially 
placed intercoolers. 2,3 ’ 15 

In a series of reports 11 a number of different types 
of high-pressure exchangers are described and some 
test data given. These exchangers have to do with 
the compact high-pressure liquid oxygen generators 
of Keyes and A. D. Little-Latham design. 11 ’ 17 

711 REGENERATORS 


This provides a basis for application of equation 
(17) to other exchangers, assuming 




(19) 


where v equals the gas velocity and the G refers to 
the Giauque equation (17). 

The procedure for calculating pressure drop con¬ 
sists then of solving equation (18) at design condi¬ 
tions to obtain P G , and then substituting this value 
in equation (19) and solving for A P. This method 
has been tested in practice and found satisfactory. 


Heat exchangers are a basic part of any low-tem¬ 
perature process for the liquefaction and separation of 
air components. Where the size of a plant is of major 
importance a good deal of attention must be given to 
the design of the exchanger so that maximum effi¬ 
ciency on a volumetric basis is realized. In consider¬ 
ing the design of oxygen plants to be fitted into very 
limited quarters the potentialities of the regenerative 
type of heat exchanger were recognized. Such an 
exchanger has a large heat transfer capacity on a 
volumetric basis coupled with a very low resistance. 
An additional feature of the regenerator, which added 









DIAMETER -7 

(COARSE STEEL PACKING) 


132 


HEAT EXCHANGE 





Figure!!. Typical flow sheet for regenerator tests. 





























































































































REGENERATORS 


133 


to its attractiveness, is that removal of impurities 
from the process air is accomplished in the regener¬ 
ator itself, eliminating the necessity of a preliminary 
cleanup system. 

Although regenerators were employed in Germany 
in air liquefaction cycles, the amount of data avail¬ 
able for use in the design of regenerator systems was 
very meager. To supply the need for such data an 
investigation was undertaken to determine the per¬ 
formance characteristics of several types of regen¬ 
erator packings. These packings were patterned 
after those described in patents taken out by Frankl 
in Germany. The object of the experimental tests 
was to evaluate the heat transfer and purification per¬ 
formance of the regenerators and determine the ef¬ 
fects of various operating variables. 

Five different types of packing were tested. 6 - 9 
Each packing was made up of two parallel crimped 
ribbons with the direction of crimp at right angles to 
each other (see Figure 22, Chapter 8). These two 
crimped ribbons were wound into a close spiral to 
form pancakes of the desired diameter. The basic 
dimensions of the packings tested are given in the 
following table. 


tory and a check valve assembly was substituted. The 
check valves (4) were arranged so that a flow re¬ 
versal initiated at the warm end by the four-way 
valve was automatically completed at the cold end by 
the action of the check valves. The cycle controller 
used permitted variations in the time interval between 
flow reversals. 

For the cold testing of the regenerators, two re¬ 
frigeration procedures were used. In the first, air, 
after being cooled in the regenerator, was bubbled 
through liquid air and then returned to the particular 
regenerator which was being cooled. The amount of 
refrigeration used could be controlled by by-passing 
some of the air around the liquid air container. The 
use of liquid air as a refrigerant required the opera¬ 
tion of a separate liquefaction plant and was costly 
and troublesome. It was later supplanted by an ex¬ 
pansion engine. This expansion engine was a new 
development and gave some early mechanical trouble 
but in the long run proved a simple and easily con¬ 
trolled source of refrigeration. 

The arrangement of the regenerators and auxil¬ 
iaries is illustrated by the typical flow sheet of Figure 
11. Table 5 presents a tabulation of some of the 


Table 4. Packing dimensions. 



3-in. 

aluminum 

7-in. 

aluminum 

7-in. 
fine steel 

7-in. 

coarse steel 

4*4-in. 

copper 

Height of crimp, in. 

0.047 

0.047 

0.0218 

0.047 

0.0417 

Pitch of crimp, in. 

0.1275 

0.1275 

0.0625 

0.1275 

0.091 

Thickness of strip, in. 

0.013 

0.013 

0.013 

0.013 

0.015 

Width of strip, in. 

0.844 

0.844 

0.867 

0.867 

0.97 

Per cent voids 

67.8 

70.0 

55.7 

69.1 

61.9 

Lb metal per cu ft 

51 

50 

213 

151 

198 


The three essentials to the regenerator test setups 
were a compression system, a flow reversal system, 
and a refrigeration system. Two different types of 
standard compressors were used, and provisions 
were made to remove all entrained oil and water from 
the air to be processed. Scrubbing towers were also 
installed in conjunction with the compression system 
to permit removal of carbon dioxide from the air 
when that was desirable. 

During the early tests on the regenerators flow 
reversal was accomplished by the simultaneous action 
of two four-way valves of the plug type, one at each 
end of the regenerators. The four-way valves were 
activated by an air operated plunger which in turn 
was operated by a cycle controller. Because of leak¬ 
age and freezing, the use of a plug-type valve at the 
cold end of the regenerators was judged unsatisfac- 


characteristics distinguishing the various test setups. 9 

In making a test the inlet air pressure, temperature 
and humidity, the flow rate, the reversal time and 
cold end temperature level were set. Pressure con¬ 
trol was provided by a pressure regulator and in 
most cases saturated air at a given temperature was 
supplied by a saturator system which included a 
water pump, gas-fired heater, and entrainment sep¬ 
arator. The air passed through one regenerator and 
was then throttled into a distributor immersed in 
liquid air. The flow rate was controlled by this 
throttle valve. After passing through the liquid air, 
the air returned through the second regenerator and 
after passing through a surge drum was metered to 
the atmosphere. At intervals set for the given run 
the flow through the regenerators was reversed so 
that the regenerator, which gave up its cold to in- 







134 


HEAT EXCHANGE 


coming air during one phase of the cycle, absorbed 
cold from the return air during the next phase of 
the cycle. This reversal was not only essential to the 
heat transfer performance of the regenerators, but 
also provided for purification of the process air by 
re-evaporating, on the low-pressure phase of the 
cycle, the water and carbon dioxide deposited out 
during the high-pressure phase. 


after it had passed through the regenerator on high 
pressure. 

The experimental data obtained in the course of the 
regenerator investigation are presented in summary 
form in a series of reports. 7 ’ 8,9 These data present a 
rather complete survey of the purification perform¬ 
ance and the heat transfer and flow resistance char¬ 
acteristics of the particular packings studied. 


Table 5. Essential differences of regenerator assemblies. 


Cold end 

No. Packing type Insulation Flow reversal Refrigeration C0 2 filter Runs made location Miscellaneous 


1 

7-in. aluminum Vermiculite 

Hot and cold 

Liquid air High pressure 

1 through 3 

Top 



Nopak 4-way 

boiled by air only 





valves 

bubbling the 
main air thru it. 



2 

3-in. aluminum 

(i 

a u 

4 through 23* 
and 50 through 57 

Bottom 

3 

7-in. aluminum “ 

Hot 4-way 

Glass wool 

58 through 76 

Bottom 



valve and cold 

after both 





check valves 

regenerators 



4 

7-in. fine steel 

<< 

Expander 

77 through 87 

Bottom 

5 

7-in. coarse steel 

H 

it (( 

88 through 100 

Bottom 


and conical 
screens between 
regenerators 
and filters 


Piping enlarged. 
Additional 
“Knock-out 
drum” for 
removing 
entrained water 
from feed. 


6 4p2-in. copper Mineral Hot Homestead 

wool 4-way valve and 

cold check valves 


Screens and 101 through 127 

Top Equalizer to 

cold filters 

damp out tem¬ 

removed. Two 

perature fluctua¬ 

new filters 

tions provided. 

installed. 

Regenerators 
were altered in 
length consid¬ 
erably in these 
runs. 


* There were no runs numbered 24 through 49. 


Once test conditions had been established and a 
steady state reached throughout the unit, pertinent, 
temperature and pressure data were taken. Because 
of the unsteady nature of the process, temperature 
histories were obtained during the course of a cycle. 
Temperatures for both gas and regenerator packing 
were taken, although in many cases the extent of the 
packing temperature data was very limited. For each 
type of packing a series of runs was made in which 
the inlet temperature, flow rate, or cycle time was 
varied independently. In the case of the 4 y 2 in. di¬ 
ameter copper packing, the regenerator length was 
also varied. Another variable studied to a rather 
limited degree was the effect of the ratio of high- 
pressure to low-pressure flow. Control of this vari¬ 
able was achieved by drawing off a fraction of the air 


It was found that when treating air, containing 
water and carbon dioxide as impurities, complete re¬ 
moval of the carbon dioxide during the low-pressure 
phase of the cycle was not accomplished, and as a 
result, there was a gradual plugging of the regener¬ 
ators, leading eventually to excessive pressure drops 
and a forced shutdown. As a result it was necessary 
to remove the C0 2 by scrubbing when making tests 
on the regenerators so that the necessary data on 
heat transfer were obtained without introducing the 
additional variables caused by plugging. Another 
impurity, which appeared to overtax the purification 
capacities of the regenerators, was entrained oil, and 
its thorough removal by filtration was found neces¬ 
sary. In the case of water the regenerators seemed 
to perform satisfactorily and no plugging trouble was 







REGENERATORS 


135 


encountered from this source. The plugging with 
C0 2 can be explained on a theoretical basis as due to 
cold end temperature differences which were greater 
than the maximum permissible for re-evaporation 
during the low-pressure phase of the cycle. It was 
thought that in large plants this temperature ap¬ 
proach could be reduced to the point where the re¬ 
generators could handle C0 2 satisfactorily. This was 
not found to he true and it was eventually discovered 
that carbon dioxide removal could only be accom¬ 
plished in a reversing cycle by special procedures. 

The experimental data on the regenerators pre¬ 
sented a mass of information which proved rather 
difficult to reduce to a useful state for design pur¬ 
poses. This difficulty arose for the most part from 
the unsteady nature of the heat transfer process. 
Theoretical approaches investigated proved rather 
cumbersome for practical application. To provide 
some sort of correlation for design purposes, a rather 
simple and admittedly unsatisfactory method was 
used. From the observed data it was possible to 
compute the amount of heat transferred in a given 
regenerator per unit time. It was also possible to de¬ 
termine the average air temperature during each 
phase of the cycle at both ends of the regenerator. 
Considering the regenerator analagous to a recuper¬ 
ator, the average gas temperatures during each phase 
of the cycle define a temperature difference at each 
end of the regenerator. Using these temperature 
differences to fix the driving force, and knowing the 
heat load and packing area or volume of the regener¬ 
ators, it was possible to calculate an overall heat 
transfer coefficient. Such a calculation involves cer¬ 
tain assumptions which are not completely fulfilled 
in the regenerator, that is, that heat leak is negligible, 
and that there is no hysteresis in the metal packing. 
The nature of the assumptions introduces a note of 
uncertainty but it was felt that coefficients calculated 
in this manner would provide some comparison be¬ 
tween the various packings tested and would be of 
some value for design purposes. 

It was found that the heat transfer results could 
be correlated rather roughly by the following equa¬ 
tion 


U h — A -\- B 


/ M 0 - 7 \ 
V*! O- 3 # 0 - 2 */’ 


( 20 ) 


in which Uh = overall heat transfer coefficient Btu 
per hr per ft 2 F. 

M = average flow rate, moles per hr. 
t 1 = entrance temperature, F. 

6 = full cycle time, min. 


The constants A and B have the following values: 


Packing 

A 

B 

3-in. aluminum 

-1.71 

+7.29 

7-in. aluminum 

-0.19 

+ 1.90 

7-in. coarse steel 

-0.6 

+3.47 

7-in. fine steel 

-0.28 

+1.76 

4*4-in. copper 

-0.38 

+3.84 


With equation (20) it is possible to compare the 
packings. Thus at a low value of the correlating 
group, for example, 0.3, these coefficients result: 


Packing 

Uh 

4^4-in. copper 

0.77 

3-in. aluminum 

0.49 

7-in. coarse steel 

0.44 

7-in. aluminum 

0.38 

7-in. fine steel 

0.28 


At a high value for the correlating group, for ex¬ 
ample, 0.8, these coefficients result: 


Packing 

Uh 

4j4-in. copper 

2.69 

7-in. coarse steel 

2.18 

7-in. aluminum 

1.34 

7-in. fine steel 

1.13 


It is therefore apparent that on an area basis, at 
least, the heat transfer coefficient is best for the 4^4- 
in. copper packing. 

If comparison on a unit volume basis is desired, 
the above coefficients should be multiplied by the 
following factors: 


Packing 
3-in. aluminum 
7-in. aluminum 
7-in. fine steel 
7-in. coarse steel 
4^4-in. copper 


Conversion factor 
579 
535 
864 
517 
654 


It is at once apparent that the copper packing 
maintains its superiority when compared on a volume 
basis. 

For comparison on a weight basis, the following 
factors should be applied to the coefficients: 


Packing 
3-in. aluminum 
7-in. aluminum 
7-in. fine steel 
7-in. coarse steel 
4}4-in. copper 


Conversion factor 
9.8 
10.56 
3.96 
3.4 
3.3 


On this basis copper maintains its superiority to 
steel but it falls behind aluminum. However, a 
volumetric basis is generally of greater significance 
and it can be concluded with some assurance that the 
copper packing is best for heat transfer. 





136 


HEAT EXCHANGE 



Figure 12. “J” tray fractionating tower showing regenerator. 



























































































































































REBOILERS 


137 


In the course of each test run on the regenerators, 
pressure-drop data were taken but since in all cases 
the values were very low, no serious attempt was 
made to correlate the pressure drop information. 
During the low-pressure phase of the cycle when pres¬ 
sure drop becomes noticeable, values ranging from 
1 to 6 psia were observed. The lowest pressure drop 
was exhibited by the 7-in. aluminum packing, after 
which followed in order of increasing pressure drop, 
the 4^2-in. copper, 3-in. aluminum, 7-in. coarse steel, 
and 7-in. fine steel packing. For the original pressure 
drop data the reports cited earlier should be con¬ 
sulted. 

In conclusion, it is felt that valuable information 
relative to the performance characteristics of regen¬ 
erators was provided by the investigation. 6 ’ 15 Num¬ 
erous difficulties were experienced but they were in 
the main overcome, and sufficient quantitative data 
were collected for design purposes. These data are 
complete enough to show the general performance to 
be expected and the effects thereon of the principal 
design conditions and operating variables. Later 
these data were used in the design of regenerators 
to be incorporated into oxygen plants. The regen¬ 
erators performed satisfactorily except for plugging 
with carbon dioxide, a problem which became evi¬ 
dent during the experimental studies. 

7-i2 REBOILERS 

A typical condenser-reboiler used at the bottom of 
the single fractionating tower 6 is shown in Figure 
12. The unit consists of a large number of small- 
diameter vertical tubes soldered to a fixed tube sheet 
at the lower end and to a floating head at the upper 
end. The cold air to be condensed enters the floating 
head and condenses on the inside of the tubes through 
transfer of heat to oxygen boiling on the outside of 
the tubes. The liquid air drains down into a collect¬ 
ing pot below the fixed tube sheet, and if the heat 
transfer surface is greater than necessary to ac¬ 
complish the condensation, the liquid air level rises 
into the tubes to blank off the excess surface. Thus 
the condenser is self-controlling. 13 ’ 18 The oxygen 
vapor boiled off must flow radially outward to the 
outside of the floating head before rising into the 
fractionating section of the tower, but no serious 
vapor-binding in the closely spaced small tubes has 
been noticed. 6 

Since only a completely liquid stream leaves the 
condenser, the small quantities of noncondensable 


gases in the air, notably hydrogen and helium, unless 
appreciably soluble in the liquid air, will accumulate 
in the condenser and reduce the rates of condensa¬ 
tion. It is standard practice to bleed off continuously 
a very small stream of gas from the condenser vapor 
space to prevent such an accumulation of noncon¬ 
densables. 

Reboilers are usually designed from a heat transfer 
standpoint using condensing coefficients predicted 
from conventional correlations and using boiling co¬ 
efficients which have been obtained experimentally 
with a single copper cylinder electrically heated and 
immersed in boiling liquid. Boiling coefficients for 
air, oxygen, methane, and ethane were measured and 
the results 12 are shown in Figures 13 and 14. The 
lowest values are used for design purposes rather 
than the best correlation. Temperature differences 



Figure 13. Individual heat transfer coefficient from 
metal to boiling air in Btu/(hr) (sq ft) (F). 



Figure 14. Individual heat transfer coefficient from 
metal to boiling oxygen in Btu/(hr) (sq ft) (F). 





138 


HEAT EXCHANGE 


of about 10 F and overall coefficients of about 150 Btu approximately countercurrent flow of boiling oxygen 

hr -1 ft -2 F _1 are common. No reliable measurements and condensing air, and effecting differential distilla- 

of overall coefficients have been made, but plant oper- tion of the oxygen, has been used and described. 10 

ating experience indicates that coefficients predicted An analysis of the theoretical advantage of this re- 

are conservative. A different type of reboiler using boiler in improving fractionation has also been given. 4 



Chapter 8 

LIQUID AIR FRACTIONATION 

By /. H. Rushton 


81 INTRODUCTION 

I n the work of Section 11.1 for the development 
of a number of oxygen-producing plants varying in 
size and in application, it soon became apparent that 
for most applications, units producing oxygen by the 
low-temperature fractionation of liquid air would be 
the most desirable, although considerable study and 
development would be needed to obtain the optimum 
in compactness, weight, simplicity and performance. 
Consequently, an extensive development program was 
initiated to provide the liquid air fractionation data 
so necessary to achieve the aims outlined. 

This chapter covers the actual experimental data 
obtained in the program, performance data on oper¬ 
ating units, and fundamental physical data pertinent 
to the study. The information is of use in the design 
of new units and in the analysis of results from and 
the evaluation of operating units. 1 

The following subjects are summarized: 

1. Various types of liquid air fractionation systems. 

2. The basis for correlation of tower performance. 

3. Vapor-liquid equilibrium relationships and their 
use in tower design. 

4. The efficiency and capacity of 23 different tower 
packings tested in a 2-in. laboratory column. 

5. Performance tests on three types of packing and 
one type of tray in full-scale mobile oxygen unit 
towers. 

6. Performance tests on nine different trays, six of 
which were developed by the use of an air-water 
testing technique. 

7. Performance tests of Steelman packing and one 
type of tray on a rocking platform simulating the 
motion of ships at sea. 

8. The performance and design of fractionating 
towers in the various units sponsored by NDRC. 

9. Summary of data pertinent to the design of 
towers. 

A list of the units which are discussed with re¬ 
spect to the fractionation equipment follows. All ex¬ 
cept the Independent Engineering Company plant are 
the result of NDRC development. 


Designation 

of Unit Description of Unit 

M-l M. W. Kellogg Co. high-pressure, two-trailer 
1,000 scfh gaseous unit 

M-2R M. W. Kellogg Co. low-pressure, two-trailer 
1,000 scfh gaseous unit 

M-3 M. W. Kellogg Co. air-transported 400 scfh gas¬ 
eous unit 

M-4 W. F. Giauque high-pressure, single-trailer liquid 
(60-84 lb per hr) unit 

M-5 M. W. Kellogg Co. low-pressure shipboard pilot 
plant liquid (400 lb per hr) unit 
M-6 M. W. Kellogg Co.-Air Reduction Co. medium- 
pressure shipboard pilot plant liquid (400 lb 
per hr) unit 

M-7 M. W. Kellogg Co.-Clark Bros. Co. Inc. low- 
pressure single-trailer 1,200 scfh gaseous unit 
M-8 M. W. Kellogg Co.-Clark Bros. Co. Inc. low- 
pressure experimental gaseous unit 
M-10 Air Reduction Co. high-pressure, single-trailer 
400 scfh gaseous unit 

M-ll F. G. Keyes high-pressure portable liquid (17-35 
lb per hr) unit 

M-12 Arthur D. Little-Latham high-pressure port¬ 
able liquid (17 lb per hr) unit 
M-13 Collins-McMahon low-pressure portable (150 
scfh) gaseous unit 

M-27 M. W. Kellogg-Central Engineering Laboratory 
low-pressure experimental gaseous unit 
M-31 M. W. Kellogg-Central Engineering Laboratory 
Le Rouget experimental liquid unit 

. M. W. Kellogg-Fort Belvoir experimental 800 

scfh gaseous unit 

. E. B. Badger Co. high-pressure portable liquid 

unit 

. Independent Engineering Co. high-pressure mo¬ 
bile gaseous unit 

As a result of the research program, NDRC now 
has available: 

1. A close-spacing tray which is more efficient in 
the utilization of height in the larger installations than 
any other known fractionation medium. 

2. Detailed information on the behavior in the 
fractionation of liquid air of twenty-three repre¬ 
sentative types of packing. 

3. Vapor-liquid equilibrium data necessary for 
the prediction of tower performance. 

4. Extensive and accurate knowledge of the oper¬ 
ation of some different types of tower system. This, 
with the information on trays, packing and equilibria, 
enables a tower design to be made for any applica¬ 
tion. 

5. Experimental information on the performance 
of some columns under rocking conditions. 


139 





140 


LIQUID AIR FRACTIONATION 


8 2 FRACTIONATION OF AIR 

The oxygen production of a unit is dependent upon 
the performance of each of its component parts. 
However, for any specified rate of oxygen production 
and purity, the efficiency of oxygen recovery from 
air in the distillation process plays a large part in 
setting the amount of air which must be handled by 
the unit, and hence the size of the equipment needed 
to supply and treat this air. 

In the distillation or fractionation process, the 
liquid feed is introduced at the top of the tower and 
travels downward in intimate contact with rising 
vapor. The oxygen, less volatile than the other con¬ 
stituents of air, tends to concentrate in the liquid as 
it falls toward the bottom of the tower. Here the 
liquid is reboiled, and the product may be withdrawn 
as either liquid or vapor. The vapor formed by re¬ 
boiling rises up the tower countercurrently to the 
liquid. The amount and purity of the product which 
may be withdrawn depend upon the length of the 
region in which the vapor-liquid contacting occurs, 
and the efficiency with which it is accomplished. 
This means that for any given percentage of oxygen 
recovery and efficiency of contacting, one dimension 
of a tower, the height, is independent of the size of 
the oxygen unit. Therefore, in order to keep the 
tower size commensurate with the unit size in small 
plants it was necessary either to find some means of 
increasing the contacting efficiency, or to accept a 
lower oxygen recovery. 

In distillation, two general types of towers are 
in use: one in which the vapor-liquid contacting is 
done successively in bubbling plates or trays, and the 
other in which the tower is filled with some sort of 
packing, to increase the wetted area available for 
continuous vapor-liquid contacting. 

At the beginning of the project no data were avail¬ 
able on the use of packing in liquid air fractionation 
and only a very meager amount on the use of tray 
towers. The available information indicated that 
towers used in the oxygen industry varied from 10 to 
20 ft in height. Since the available tower height was 
limited, it was necessary to study fractionation equip¬ 
ment, its operation, and some of the fundamental 
physical data of air. 2 

8 21 Tower Systems 

There are a number of different arrangements of 
fractionating towers in use in the separation of 
oxygen from liquid air. Some of the more common 
systems are shown in Figure 1. The choice of sys¬ 


tem to be used in any particular unit depends upon a 
number of factors which include, among others, the 
type of liquefaction or refrigeration cycle used. 

Simple Single Liquid Feed Tower 

This is the simplest of all the liquid air fractiona¬ 
tion columns, and can be used with any refrigeration 
cycle. The high-pressure air feed is condensed in the 
reboiler by the vaporizing oxygen. The condensed 
air is expanded through a valve down to the tower 
pressure and introduced at the top of the fractionator. 
The liquid travels downward through the tower in 
countercurrent contact with the rising vapors. Oxy¬ 
gen may be withdrawn either as vapor or liquid 
product from the boiling side of the reboiler, while 
the waste gas passes out the top of the tower. 

A fraction of the high-pressure liquid is vaporized 
in expanding to the tower pressure. This lowers the 
quantity of liquid reflux fed to the tower and de¬ 
creases the oxygen recovery. This effect may be 
partially overcome by subcooling the liquid by heat 
exchange with the waste nitrogen. The condensing 
pressure should thus be kept as low as possible but 
the proper heat transfer in the reboiler should be 
maintained. 

Because the liquid feed at the top of the column 
is air, the waste overhead gas always contains an ap¬ 
preciable amount of oxygen. At atmospheric pressure 
this fact limits the oxygen recovery to about 60 to 
70% of the oxygen in the air feed. Increasing the 
tower pressure decreases the maximum recovery 
by lowering the relative volatility of oxygen and 
nitrogen. 

The maximum theoretical recovery as a function of 
tower pressure is shown in Figure 2. Two cases are 
shown, one in which the operating conditions are 
those encountered in actual towers, and the other, 
the idealized case in which the liquid condenses at 
its minimum pressure (that is, with zero tempera¬ 
ture difference across the reboiler), is subcooled, and 
with no heat leak to the column. 

The height restriction in the portable units indi¬ 
cated the use of single towers, even though the low 
oxygen recovery is a disadvantage. Some of the 
towers, such as the one in the Collins-McMahon 
unit, 4 are too short even to approach the theoretical 
recovery. Often when the oxygen is withdrawn as 
liquid product, the yield is limited by the amount of 
refrigeration available, rather than by the distillation 
process. In this case the lower maximum yield of a 
single tower is not a disadvantage. 




FRACTIONATION OF AIR 


141 


SINGLE TOWERS 






ordinary single tower 

FORT BELVOIR 

LATHAM 

COLLINS 

KEYES 

AIRCO 


HIGH PRESSURE AIR FEEO 
700-900 LBS/SQIN 


SINGLE TOWER WITH COUNTER 
CURRENT VAPOR FEED 
MODIFICATION 

M— 2 R. M—6, 

M—7, M — 6 


SINGLE TOWER WITH 
CON-CURRENT VAPOR 
FEED MODIFICATION 
M-5 


SINGLE TOWER WITH 
PREFRACTIONATOR 

M—2 



KEYES DUPLEX RECTIFIER 
TOWER B OPERATES 
AT A SLIGHTLY HIGHER 
PRESSURE THAN TOWER A 

(NOT USED ON A UNIT) 


WASTE 


DOUBLE TOWERS 



WASTE 

NITROGEN 


100 LBS /SO IN. 

EXPANDER 
AIR 

INDEPENDENT ENGINEERING CO 
MODIFICATION OF DOJBLE TOWER SYSTEM 




W F GIAUOUE 
MODIFICATION OF DOUBLE 
TOWER SYSTEM 


HIGH PRESSURE AIR FEED 
M —I TOWER SYSTEM 


DOUBLE COLUMN 
LOW PRESSURE SYSTEM 


OOUBLE COLUMN 
HIGH PRESSURE SYSTEM 


Figure 1. Liquid air fractionation tower systems. 


Another advantage of the single tower is its sim¬ 
plicity of operation. Since expert personnel may not 
always be available for operation of these units, this 
item is of importance. 

Single towers have been used in most of the units 
built for the Armed Forces. 


200 


to 

03 

< 


O 

<r> 


to 

03 


to 

CO 

UJ 

CL 

a. 

tr 

UJ 

l 


100 
90 
80 
70 
60 
50 
40 

30 
20 h 


10 
























































- 

BASIS OF COMPUTATIONS \ N 




LINE A LINE B A 




HEAT LEAK 1 BTU/LB OF AIR NONE 

- TEMP DIFFERENCE 9° F 0* F 

_ ACROSS REBOILER 

WASTE NITROGEN USED NO YES 

TO SUBCOOL REFLUX 
(AT = 0°F ) 

A \ 

v \ 




V\ 

B 


















5k_ 


10 20 30 40 50 60 70 

PER CENT OXYGEN RECOVERED FROM OXYGEN IN FEED 


80 


90 


Figure 2. Effect of pressure on maximum theoretical 
oxygen recovery for single tower operation. 


Single Tower with Vapor Feed Modifications 

In some low-pressure units, refrigeration is sup¬ 
plied by expansion of a part of the air supply through 
an engine to tower pressure. Air so used does not 


go to the condenser and is thus lost to the recovery 
system as liquid feed, but some of the oxygen may 
be recovered from this vapor if it is contacted with 
the liquid feed. This may be done either counter- 
currently as in the M-7 unit, or concurrently, either 
inside the tower as in the M-5 unit, or outside of the 
tower with a prefractionator as in the M-2 unit. The 
choice between these tw r o alternatives depends upon 
the height available, the mechanical design of the 
tower system, and the specific purpose of the unit. 
The effect of these factors on the M-5 design is dis¬ 
cussed later. 

Concurrent contacting is equivalent to an equilib¬ 
rium flash vaporization of air in which the liquid 
composition may vary from 21% oxygen at 0% 
vapor to 50% oxygen at 100% vapor. This contact¬ 
ing of liquid and vapor feeds does not change the 
quantity of liquid reflux but instead provides a richer 
feed to the fractionating section, and by so doing 
gives a higher oxygen recovery. 

With an infinitely large ratio of vapor to liquid 
feed, there is no difference between the two methods 
of contacting. However, with the ratio of liquid to 
vapor encountered in this program, a higher oxygen 





















































































































































































































































































































































142 


LIQUID AIR FRACTIONATION 


recovery is made by using the countercurrent system. 
The introduction of vapor feed at some intermediate 
point in the tower forms a rectifying section in which 
some of the oxygen in the vapor feed may be stripped 
out. 

With either of these systems the maximum theo¬ 
retical recovery of oxygen is about 125% of the 
oxygen in the liquid feed. 

For the conditions encountered in the portable 
units the vapor feed system probably gives a better 
utilization of height than the double tower system. 
The units built by Clark Brothers Company have 
columns of this type. 

Keyes Duplex Rectifier 

Although this system has two towers it is still a 
single column in principle. It has not yet been used 
on a unit, and is included here as an example of one 
of the many possible arrangements which can he 
used to reduce column height. The two columns 
fractionate the liquid in series. The crude oxygen 
from the first is purified in the second. At the top of 
the second tower the waste nitrogen condenses some 
crude oxygen vapor, thereby furnishing more reflux. 
It is a modification of the subcooler principle and 
can give an absolute maximum yield of not over 75%. 

Simple Double Column 

It has been mentioned that the yield of a single 
column is limited because of the oxygen content of 
the liquid air feed. The term double column refers 
to a fractionating tower which has, below the reboiler, 
a rectifying section in which pure nitrogen reflux is 
produced. Two types of standard double towers are 
shown in Figure 1. Neither of these has been used on 
an NDRC unit. 

In the simpler of these two types the high-pressure 
air feed is introduced at the bottom of the lower 
section. Reflux to this fractionating section is fur¬ 
nished by condensing nitrogen in the reboiler by 
means of the boiling oxygen. About 40% of the air 
feed is withdrawn as liquid nitrogen from the top 
of the high-pressure section and introduced as re¬ 
flux at the top of the low-pressure section. The re¬ 
maining fraction of the liquid air feed is taken from 
the bottom of the high-pressure section and intro¬ 
duced somewhere near the center of the low-pressure 
section. 

In the system described, the maximum yield calcu¬ 
lated from present equilibrium data is about 90% 


of the oxygen in the liquid air feed. With vapor feed 
in the low-pressure tower, the recovery can approach 
125% of the liquid feed as it does with the single 
tower with vapor feed. 

Compound Double Column 

The second type of double column may be used 
when the head pressure is high enough to use another 
reboiler in the bottom of the high-pressure tower. 
The liquid from this condenser may he then intro¬ 
duced at a mid-point in the high-pressure tower. 
With this modification it is possible to recover prac¬ 
tically 100% of the oxygen in the total air feed, as¬ 
suming no vapor feed. 

Aside from the obvious advantage of complete 
oxygen recovery, this column can simultaneously 
produce a pure inert gas from the top of the tower. 
This system is out of the question for portable units 
unless an ultraefficient tower packing is developed. 

A disadvantage of both double types of double 
columns is the difficulty of control, as there are three 
streams to he analyzed, and three liquid levels to be 
controlled. However, the experimental column of the 
M-31 plant was found to he about as easy to control 
as the single columns. 

Independent Engineering Company 
Double-Tower System 

This system, as orginally used on the mobile 
oxygen units manufactured by the Independent En¬ 
gineering Company of O’Fallon, Illinois, is an at¬ 
tempt to reduce the height of a double tower by plac¬ 
ing the high and low-pressure sections side by side. 
However, when this is done, there is no way in which 
reflux may he supplied to the top of the high-pressure 
tower. 

In the cycle used in these units, 6 a portion of the 
high-pressure air feed is expanded through an engine 
from about 800 psi to 100 psi. This air is fed as 
vapor to the bottom of the high-pressure tower. The 
remainder of the air compressed is introduced at the 
mid-point of the high-pressure tower. The quantity 
of liquid reflux at this point is set by the heat balance 
of the tower system and is about 10% to 15% of 
the total amount of air. 

The liquid, which contains about 40% oxygen, 
withdrawn from the bottom of this tower is fed to an 
intermediate point in the low-pressure tower. The 
overhead high-pressure vapor is condensed in the 
reboiler and then fed as reflux to the top of the low- 



THEORY OF LIQUID AIR FRACTIONATION 


143 


pressure tower. The theoretical maximum oxygen 
recovery with this system is about 10% greater 
than is possible with a single liquid feed tower. 

M-l Double-Tower System 

This tower arrangement is an attempt to attain 
double tower yields in a limited height. 

The low-pressure tower has a reboiler which is 
divided into two sections on the condensing side. 
Part of the high-pressure air feed is liquefied in one 
of these sections. The remainder of the air feed is 
sent to the bottom of the high-pressure tower, where 
it is fractionated. Reflux is supplied by the latent 
heat of vaporization of the vaporizing liquid oxygen 
product and the sensible heat of the waste gas from 
the low-pressure tower. Uncondensed vapor passing 
through this condensing section is then liquefied in 
the second section of the reboiler from which the 
liquid is fed to the top of the low-pressure tower. 
The liquid from the bottom of the high-pressure 
tower is mixed with the condensed air and intro¬ 
duced to an intermediate point in the low-pressure 
tower. The maximum theoretical oxygen yield of 
this system should be 95% to 100%. 

Giauque Modification of the Double Tower 

This tower is classed under double towers be¬ 
cause nitrogen reflux is prepared outside of the 
low-pressure column. In this alteration of the double¬ 
tower system a 100% oxygen yield may be made by 
recirculating the tower overhead to increase the 
amount of liquid reflux. 

In the system, as planned by Giauque of the Uni¬ 
versity of California for his portable unit for NDRC, 
the tower is built with the condensing side of the 
reboiler divided into two sections. 7 The high-pres¬ 
sure air feed is liquefied in one of these sections and 
then fed to some intermediate tray in the tower. 
Part of the waste gas leaving the tower is warmed to 
room temperature, compressed to about 100 psi, re¬ 
cooled and then liquefied in the second section of the 
reboiler. From here the liquid is fed to the top of 
the tower. 

By increasing the amount of recirculated nitrogen, 
the separation of oxygen from liquid air is made 
easier, and the tower may be shortened. It is 
possible to make a perfect recovery of the oxygen 
in the incoming air in a very short tower, but this 
benefit will be at the expense of power and of re¬ 
frigeration loss in the recirculating nitrogen. In 


order to attain the perfect oxygen recovery, the 
theoretical minimum amount of nitrogen which must 
be recompressed is 70% of the air feed. 

8 3 THEORY OF LIQUID AIR 

FRACTIONATION 

8 31 Basis of Correlation 

The research in liquid air fractionation has fol¬ 
lowed two definite lines, namely, fractionation in 
laboratory size equipment and in towers of the size 
used in portable units. Some basic measure of frac¬ 
tionating ability must be used to reconcile the effects 
of height, diameter, liquid and vapor loads, type of 
packing or trays, distributors, redistributors, etc., in 
the correlation of data, as well as in the design of a 
new tower. 

In studying distillation in packed towers either one 
of two concepts is generally used as a yardstick: (1) 
the transfer unit, and (2) the theoretical plate. These 
are used as the height of packing in a transfer unit 
[HTU] and the height of packing equivalent to a 
theoretical plate [HETP]. 1 

It is often said that the HTU is the better unit to 
use because it is based upon valid integration of a 
fundamental relationship, while the use of the HETP 
applies a continuous batch contacting mechanism to 
a continuous countercurrent process. Actually, both 
units are functions of the absorption rate coefficients. 
The units are also dependent upon the value of the 
ratio of slope of the equilibrium line to the slope of 
the distillation operating line. This means that for 
any one system the HTU and HETP will vary with 
the reflux ratio. This variation with reflux ratio is 
apt to be greater for the HTU than for the HETP. 

These same two concepts are used in evaluating 
the performance of tray towers, in which applica¬ 
tion they appear as plates per transfer unit [PTU] 
and as overall tray efficiency. However, the use of 
PTU in tray towers is also subject to the criticism 
that a mechanism is implied which does not exist. 

In the research program towers made of both trays 
and packings have been investigated. Comparison 
of these two types cannot be simple unless one of the 
above concepts is used for both cases. Although there 
is not much choice between the HTU and the HETP, 
since whichever is used is theoretically unsound in 
half its application, the HETP has been chosen as a 
basis throughout this study because tray efficiencies 
are in much more common usage than the PTU. 



144 


LIQUID AIR FRACTIONATION 


In addition, it is much easier to visualize the con¬ 
cept of tray efficiency and of HETP than of transfer 
units. 


2 Methods of Tray Calculation 

The composition of air is generally accepted as: 


Component 

Nitrogen 

Oxygen 

Argon 

Carbon dioxide 

Hydrogen 

Neon 

Helium 

Krypton 

Xenon 


Mole per cent 

78.03 

20.99 

0.933 

300 X 10- 4 
100 X io- 4 
15 x 10- 4 
5 X 10- 4 

1.1 x io- 4 

0.08 X 10- 4 


For all practical purposes the traces of rare gases 
may be considered negligible, so that air is treated 
as a three-component mixture of the following com¬ 
position : 

Atmospheric Pressure 
Mole per cent Boiling Point 


Nitrogen 78.08 —320.4 F 

Oxygen 20.99 -297.4 F 

Argon 0.93 -302.3 F 


Fractionation of air is sometimes considered as the 
separation of a binary mixture of nitrogen and oxy¬ 
gen. This simplified treatment often leads to errone¬ 
ous conclusions. For instance, calculations with the 
oxygen-nitrogen binary mixture show that five per¬ 
fect plates are required at total reflux to make 
99.5% oxygen, but that only 6.5 are needed to make 
60% recovery at the same 99.5% purity. This is in 
startling contrast to operating experience. Because 
the boiling points of oxygen and argon are so close 
together, the upper part of the single tower acts as 
a nitrogen stripper, with the argon concentration 
reaching a maximum somewhere in the tower. This 
maximum concentration may be as much as 25 to 
30% depending upon the reflux ratio. Below the 
point of maximum argon concentration the pres¬ 
ence of nitrogen is negligible and the tower then acts 
essentially as an argon stripper. This sort of be¬ 
havior is typical of most multi-component distilla¬ 
tions. 

Methods of tray-to-tray calculations have appeared 
frequently in the literature. All the methods are 
fundamentally the application of successive heat and 
material balances to the concept of the perfect tray, 
which is defined as one in which the vapors leaving 
the plate are in equilibrium with the liquid leaving 
the plate. 


Computation of single feed liquid air fractionation 
is considerably simplified by the fact that the tower 
is only a stripping section and that the amount of 
nitrogen present in the oxygen product is insignifi¬ 
cant. Since only a stripping section is involved, the 
complicated calculations necessary to determine the 
proper location of the feed tray are eliminated. The 
absence of nitrogen in the product makes it possible 
to calculate from the top to the bottom directly. If 
nitrogen were present in the bottom product in an 
appreciable amount, it would he necessary to assume 
a bottoms composition and compute upwards to the 
feed tray. This process leads to a long series of 
trial and error calculations. Before any tray calcula¬ 
tions were made, the validity of the assumption that 
the effect of nitrogen is negligible was checked by 
the method of Thiele and Geddes. For instance, if 
ten perfect trays are used, it was found that at 25% 
oxygen recovery, the mole fraction of nitrogen in the 
product is 0.00001. 

If the number of trays in a tower is very low, then, 
of course, the amount of nitrogen in the product will 
he appreciable and must he considered. Actually 
this case has not occurred in the data taken. Short 
packed columns sometimes had the effect of very 
few theoretical trays, hut since these towers were 
tested at total reflux, no product was withdrawn, and 
the amount of nitrogen in the bottom does not appear 
in the calculations. 

The method used here is, therefore, simply one 
in which heat and material balances and the equilib¬ 
rium calculation are repeated for each tray from the 
top to the bottom. Due to heat leak and the fact 
that the molal heat of vaporization differs from those 
of argon and oxygen, it is necessary to correct the 
liquid and vapor quantities on each tray by successive 
heat balances. When the nitrogen content has be¬ 
come low enough, for example, 0.04 to 0.05 mole 
per cent, the stepwise balances may he omitted and the 
simple graphical method used. Algebraic tray calcu¬ 
lations frequently become tiresome, especially at the 
higher oxygen yields where the number of steps is 
large. Use of a graphical method, devised for treat¬ 
ing the fractionation of ternary mixtures simplified 
the work. This method was used in checking cal¬ 
culations. 1 

A number of stepwise calculations have been made 
to determine the number of theoretical trays re¬ 
quired for various oxygen recoveries and purities. 
These calculations are summarized by Figure 3 in 
which the oxygen concentration in the liquid leaving 




% OXYGEN IN LIQUID LEAVING PLATE 


THEORY OF LIQUID AIR FRACTIONATION 


145 



Figure. 3. Relation between oxygen concentration in liquid or plates for various yields and production purities. 





































































































146 


LIQUID AIR FRACTIONATION 



Figure 4. Relation between production purity and number of plants at constant yield. 





























































































































THEORY OF LIQUID AIR FRACTIONATION 


147 


each theoretical tray is given. By cross-plotting of 
these lines, it is possible to construct Figures 4 and 
5, which give the number of theoretical plates re¬ 
quired to produce a given purity at any operable 
yield. 

Figure 4 is based upon average single-column oper¬ 
ating conditions of: 

Tower pressure 20 psia 

Condensing pressure 90 psia 

Heat leak 2 Btu per lb of air 

No reflex subcooling 

The chart will not be greatly in error if used for 
any simple single tower at an oxygen recovery of 
50% or less. It may be used for oxygen recoveries 
as high as 60% if the conditions are such that the 


caused by inaccurate analysis of the oxygen product. 
Although the error in the actual number of trays 
becomes greater with increasing recovery, oddly 
enough the percentage error is practically independ¬ 
ent of the oxygen yield at any given analytical error 
and purity. 

The case of vapor feed towers has not been given 
such a thorough treatment because of the problem of 
locating the vapor feed. At any given ratio of vapor 
feed to liquid feed and oxygen recovery, there is one 
and only one correct location of the vapor feed. 
Therefore, any complete analysis of a vapor feed 
tower must consider five variables; product quantity 
and purity, vapor quantity, feed tray location, and 
total number of trays. Even if such an analysis were 
made it would serve only as corroboration of HETP’s 



PERCENT YIELD- -- 

MOLES OXYGEN IN FEED 


tr-J 
o< 
a: 9 


of 

aA 

UJUL 

OlO 


<a 

UJ O 


f o 

UJ 

of 


OBSERVED PERCENT OXYGEN - ACTUAL PERCENT OXYGEN 




-0.5 -0.4 -0.3 -0.2 -0J 0 OJ 0.2 0.3 0.4 0.5 

OBSERVED PERCENT OXYGEN — ACTUAL PERCENT OXYGEN 


Figure 6. Effect of errors in oxygen analysis on tray 
calculations. 


FigureS. Relation between yield and number of plants. 

amount of vaporization resulting from expansion of 
the reflux is within 20% of that of the specified 
conditions. Above a recovery of 60% the chart be¬ 
comes doubtful because of uncertainties in the equi¬ 
librium data. 

Figure 6 shows the error in estimating FIETP’s 


and tray efficiencies found in single-tower opera¬ 
tion. The performance of several tower runs with 
vapor feed has been checked, 9 ’ 12 and where analyses 
at the feed tray were available the results agreed 
closely with those runs using liquid feed only. Com¬ 
parison of HETP and HTU has been investigated 1 
and it has been found that FIETP and HTU are both 
equally applicable. 























































































































148 


LIQUID AIR FRACTIONATION 


8 4 VAPOR-LIQUID EQUILIBRIUM 

The importance of good equilibrium data cannot be 
overestimated if engineering methods are to be ap¬ 
plied in the design of oxygen units. The effect of 
unreliable data may be minimized by testing towers 
at total reflux, but such experiments can he used only 
comparatively without knowledge of equilibrium be¬ 
havior. 

Equilibrium data may be presented in a number of 
ways. In this work either the equilibrium constant, 
K = y/x, or plot of y vs x, is used where y and x 
are the equilibrium mole fractions of a component 
in the vapor and liquid phases, respectively. The 
function K is more convenient in the three-component 
tray calculations, while y vs x is used in the binary 
graphical solutions. 

There were no reliable vapor-liquid equilibrium 
data available on the three-component system 
N 2 -A-0 2 , and research was initiated to obtain them, 13 
but the three-component data (Figure 7) were ob¬ 
tained too late to be used for the plants covered in 
Chapters 3 and 4. 



-308 -306 -304 -302 -300 -298 296 -294 -292 -290 -288 -286 -284 
TEMPERATURE,DEGREES F 


Figure 7. Equilibrium data for the system nitrogen- 
argon and oxygen at two atmospheres absolute. 


Published and NDRC experimental data on the 
three possible binary systems are: oxygen-nitrogen 
(Figures 8 and 9), argon-nitrogen (Figure 10), 
argon-oxygen (Figure 11). 



Figure 8. Liquid-vapor equilibriums for the oxygen- 
nitrogen system. 


The ideal equilibrium constants computed by 
Raoult’s and Dalton’s laws are shown with the ex¬ 
perimental values for the binary systems. The agree¬ 
ment between the ideal and actual values is very good 
except in the cases of low concentration of one com¬ 
ponent. Because of this agreement, it seemed rea¬ 
sonable to assume that the ternary system would also 
behave ideally. The deviations from the ideal equi¬ 
librium constants occur in composition ranges which 
are not encountered in liquid air fractionation, except 
in the removal of nitrogen, and in the section of a 
tower where only argon and oxygen are considered. 
Data used for column design are given in Table 1. 

Fortunately nitrogen is so much more volatile 
than oxygen or argon that it is stripped out very 
quickly, so that a considerable error in the nitrogen 
K makes little difference in the oxygen and argon 
composition. When the nitrogen is out, the Aston 
data are applicable. 10 

8 5 TRAY EFFICIENCIES 

In evaluating the efficiency of mass transfer in 
trays two different concepts are used. These are 
the Murphree efficiency and the overall tray effi¬ 
ciency. The Murphree efficiency is defined as the 
change in composition that would be accomplished 

















































































TRAY EFFICIENCIES 


149 


1.0 
0.9 
0.8 
0.7 
x 0.6 

> 0.5 

“ 0 4 
x 

0.3 

0.2 


0.1 


• 









10% Nil 

1 

■R 

OGEN 

IN LIQ 

UID 


OXYGEN 

- NITROGEN EG 

UILIBRI/ 

* 2 

0% NIT 

ROGEN 

IN 

LIQUID 






PRES 

SURE - 1 ATMOSPHERE 





J \ 














































_ 
























.. M 














o? ' N ^ 

Z 










































-RA 

oult’s 

PERIME 

DOC 

AND 
NTAL 
)GE ANI 

dalton’s law 

/S 




Cl 






cx 

3 DUNB 

AR 

1C 

_ 

)% OX 

YC 

20% OXYGEN IN 

1 1 

SEN IN LIQUID 
_1_1 

LIQUID 










-322 -320 


-318 


-316 


1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 


0.1 


*314 -312 *310 *308 -306 -304 -302 *300 *298 -298 

TEMPERATURE °F 


Figure 9. K values for oxygen-nitrogen equilibriums, 1 atmosphere absolute. 



-320 -3i8 -316 -314 -312 -310 '308 306 -304 -302 *300 *298 -296 

TEMPERATURE IN DEGREES F 


Figure 10. Equilibrium data for argon-nitrogen, 1 atmosphere absolute. 


if the vapor leaving were in equilibrium with the 
liquid overflow. This definition when applied to a 
given point of vapor-liquid contact is known as the 
Murphree point efficiency. The overall efficiency is 
the ratio of the number of perfect trays necessary 


for a given separation to the number of actual trays 
required for the same task. 

The Murphree and overall tray efficiencies are 
equal only when the equilibrium and operating lines 
are parallel. The relation between the point efficiency 














































































































































150 


LIQUID AIR FRACTIONATION 



z 

2 
c n 
z 
o 
o 


tr 

m 

_j 

3 

O 

UJ 


Figure —. Equilibrium constants for argon-oxygen. 


Table 1. Nitrogen-argon-oxygen vapor-liquid equilibrium constants. K — y/x vs temperature at 1 atmosphere abs. 


Temp F 

n 2 

A 

o 2 

Temp F 

N 2 

A 

0 2 

- 316.0 

1.26 

0.465 

0.358 

— 301.5 

3.30 

1.06 

0.775 

- 315.5 

1.30 

0.475 

0.370 

— 301.0 

3.45 

1.15 

0.810 

- 315.0 

1.32 

0.490 

0.385 

— 300.5 

3.60 

1.22 

0.830 

- 314.5 

1.36 

0.500 

0.398 

— 300.0 

3.77 

1.29 

0.850 

- 314.0 

1.40 

0.515 

0.410 

— 299.9 

3.80 

1.30 

0.860 

- 313.5 

1.44 

0.530 

0.420 

— 299.8 

3.84 

1.32 

0.865 

- 313.0 

1.48 

0.545 

0.435 

— 299.7 

3.88 

1.33 

0.870 

- 312.5 

1.53 

0.560 

0.450 

— 299.6 

3.91 

1.34 

0.875 

- 312.0 

1.58 

0.575 

0.460 

— 299.5 

3.95 

1.35 

0.880 

- 311.5 

1.62 

0.590 

0.475 

— 299.4 

3.99 

1.36 

0.888 

- 311.0 

1.67 

0.605 

0.485 

— 299.3 

4.02 

1.37 

0.895 

- 310.5 

1.72 

0.620 

0.500 

— 299.2 

4.06 

1.38 

0.900 

- 310.0 

1.77 

0.640 

0.512 

— 299.1 

4.10 

1.39 

0.905 

- 309.5 

1.82 

0.660 

0.525 

— 299.0 

4.15 

1.40 

0.910 

- 309.0 

1.89 

0.680 

0.538 

— 298.9 

4.20 

1.41 

0.917 

- 308.5 

1.95 

0.700 

0.550 

— 298.8 

4.23 

1.42 

0.923 

- 308.0 

2.01 

0.720 

0.563 

— 298.7 

4.27 

1.43 

0.930 

- 307.5 

2.09 

0.740 

0.577 

— 298.6 

4.30 

1.44 

0.937 

- 307.0 

2.15 

0.765 

0.590 

— 298.5 

4.35 

1.45 

0.943 

- 306.5 

2.23 

0.790 

0.600 

— 298.4 

4.40 

1.46 

0.948 

— 306.0 

2.30 

0.820 

0.620 

— 298.3 

4.45 

1.47 

0.955 

— 305.5 

2.40 

0.840 

0.630 

— 298.2 

4.48 

1.48 

0.961 

— 305.0 

2.50 

0.860 

0.645 

— 298.1 

4.52 

1.49 

0.968 

— 304.5 

2.60 

0.890 

0.660 

— 298.0 

4.55 

1.50 

0.975 

— 304.0 

2.70 

0.920 

0.680 

— 297.9 

4.60 

1.50 

0.980 

— 303.5 

2.80 

0.950 

0.700 

— 297.8 

4.65 

1.50 

0.985 

— 303.0 

2.90 

0.980 

0.715 

— 297.7 

4.70 

1.50 

0.992 

— 302.5 

3.05 

1.000 

0.730 

— 297.6 

4.75 

1.50 

0.997 

— 302.0 

3.18 

1.03 

0.750 

— 297.5 

4.80 

1.50 

1.000 


and the tray efficiency is a function of the degree of 
liquid and vapor mixing or crossflow effect in the 
tray. Figure 12 shows this relation for these types 
of trays. 


In designing a tower, of course, only the overall 
efficiency is of any use and it is this overall efficiency 
of the trays studied which has been used in the cor¬ 
relation of tower performance. 





























EXPERIMENTAL PROGRAM 


151 


2.0 


1.9 


1.7 


w 1.6 


1.5 


1.4 


1.3 


1.2 


l.l 































c 













J 






SLOPE OF OPERATING LINE 

E 0 -OVERALL TRAY EFFICIENCY 

— WHEN J=l, OVERALL TRAY EFFICIENCY 
EQUALS MURPHREE TRAY EFFICIENCY 



















/ 






















\t> 


7^ 

o 



o> 

s* / 








X* 



->v 


\ / 



.0 



o' 

' 



0 
. T> 



oV 

U s 

UY 








<s 



































>"°-t 

/ 












A 

/ 
























* 




















0.3 


0.4 0.5 0.6 0.7 a8 0.9 

E p (MURPHREE POINT EFFICIENCY) 


1.0 


\J 




»• —-,i 






s 




nr 

1 




1 m \' 


NO LIQUID MIXING. 
COMPLETE VAPOR 
MIXING.REVERSAL 
OF LIQUID FLOW ON 
SUCCESSIVE TRAYS. 


NO LIQUID OR 
VAPOR MIXING. 
LIQUID FLOWS 
IN SAME DI¬ 
RECTION ON ALL 
TRAYS. 


NO LIQUID OR 
VAPOR MIXING. 
REVERSAL OF 
LIQUID FLOW ON 
SUCCESSIVE 
TRAYS. 


Figure 12. Effect of direction of flows on tray efficien¬ 
cies. 


8 6 EFFECT OF TOWER PRESSURE 

Atmospheric pressure equilibrium constants have 
been used exclusively although tower pressures have 
varied from 15 psia to 22 psia in the bulk of the 
experimental work, and pressures as high as 45 psia 
have been reached. Argon-oxygen data at pressures 
greater than atmospheric were not available in time 
to permit use in the initial designs. 

The effect of pressure on mass transfer is three¬ 
fold. The maximum theoretical yield decreases with 
increased pressure; the number of trays required to 
reach any yield increases with pressure; and pressure 
acts to reduce the rate of mass diffusion. As far as 
present experience goes, use of the McCabe-Thiele 
analysis with Figure 8, and the treatment of argon 
and oxygen as a single component are satisfactory for 
predicting the maximum yield (infinite plates). 

To determine the increased difficulty of fractiona¬ 
tion evidenced by the additional plates required, the 


three-component data are necessary as well as the 
correct oxygen-argon relationship. Although pres¬ 
sure may have a large influence on the number of 
theoretical trays required, no serious error will oc¬ 
cur in design of production towers if their operation 
is at substantially the same pressure as the test towers 
from which the efficiencies and HETP’s were derived. 

Unfortunately, there are no performance data 
which show clearly the loss in oxygen recovery 
caused by high-pressure operation. 

8 7 EXPERIMENTAL PROGRAM 
8 71 Small Column Tests 

The equipment and flowsheet for the liquid air 
fractionation (small column) tests are shown in Fig¬ 
ures 13 and 14. 1,14>15 

Table 2 gives a list of the packings tested and a 


Table 2. Yale University test data summary of pack¬ 
ing efficiencies and capacities in two-inch diameter 
tower. 


Packing 

Packed 
density 
lb per cu ft 

Flooding 
capacity 
lb per 

(hr) (sq ft) 

HETP at 
flooding 
point 

Berl saddles, Ya x Ya in. .. 

60 

1,520 

2.7* 

Carding teeth . 


2,520 

7.4 

Ewell spiral packing (1-in. 
dia.) . 


350 


Fiberglas No. 1 . 

0.72 

1,970 

8.6 

Fiberglas No. 1 . 

1.79 

1,510 

6.9* 

Fiberglas No. 1 . 

4.3 


6.9* 

Fiberglas No. 2 . 

21.4 


8.6* 

Fiberglas No. 3 . 

10.7 

1,490 

6.9* 

Haydite, 4-8 mesh. 

25 

l,100f 

2.7* 

Haydite, 44 in. 

25 

1,450 

4.4* 

Helices, % in. single turn, 
glass . 

43 

1,500$ 

4.2* 

Helices, %o in. single turn, 
wire . 

83 

1,450 

6.4 

Regenerator packing . 

54 

1,070 

4.7* 

Rings, Ya in. aluminum 
Lessing . 


1,550 

2.0 

Rings, Ya in. glass, 10 in. 
packed height . 


1,120 

1.6 

Rings, Ya in. glass, 18 in. 
packed height . 


1,380 

1.9 

Rings, in. glass . 


2,300 

4.2 

Rings, %2 in. long shoe 
eyelets . 

55 , 

1,630 

2.0 

Stedman, 60 x 40 mesh ... 

33 

1,700 

1.2 

Stedman, 80 x 80 mesh ... 

18 

1,400 

1.28 

Stedman, 100 x 100 mesh.. 


1,500 

1.35 

Stedman, 120 x 120 mesh. . 


800 

2.0 

Textile, metal-wire 0.006 
in. dia. 

17 

2,660 

5.9 


* Tower inclination not measured; known to be vertical in all 
runs not so marked. 

t Flooding capacity is liquid or gas rate (total reflux) at the 
top of the tower, measured at 1 atm pressure. 

| Capacity estimated from the pressure drop, value of HETP 
given is at 1,000 lb per (hr) (sq ft) feed rate. 














































































































152 


LIQUID AIR FRACTIONATION 



Figure 13. Small test column setup. 


summary of the packed densities, capacities, and the 
HETP’s at the flooding point. The efficiency of the 
packing is, in most cases, the highest at the flooding 
point. 

The HETP and pressure drop data are summa¬ 
rized in the following graphs: HETP vs feed rate, 
tower known to be vertical (Figure 15), HETP vs 
feed rate, inclination of tower not known (Figure 16), 



pressure drop vs vapor rate, Stedman packing (Fig¬ 
ure 17), pressure drop vs vapor rate, other packing 
(Figures 18 and 19), efficiencies and capacities (Fig¬ 
ure 20). 

Effect of Tower Alignment 

During the tests with Stedman packing the im¬ 
portance of the tower inclination was discovered. A 
column was insulated merely by lowering it care¬ 
fully into the cold box, which was filled with Santocel. 
With this technique it was possible for the tower to 
lean slightly. Several packings had been tested be¬ 
fore the importance of this factor had been discovered. 
The more interesting of these were retested in a 
tower known to be vertical. 

After this discovery, the effect of inclination upon 
efficiency was determined quantitatively for Stedman 
packing, shoe eyelets and glass rings. These results 
are plotted in Figure 21. Stedman packing appears 
to be more sensitive to inclination than either of the 
bulk packings. At an angle of 2 degrees from the 
vertical the efficiency of the Stedman packing is 40% 
lower than when vertical. The same tilt decreases the 
efficiency of shoe eyelets and %-'m. glass rings by 
25% and 15% respectively. In addition, inclination 
increases the capacity of Stedman packing. The flood¬ 
ing point in the early runs is as much as 50% higher 
than the capacity determined in the vertical tower. 
Although no flooding points were obtained for the 
bulk packing, when tilted, the pressure drop was not 


































































































EXPERIMENTAL PROGRAM 


153 


LIQUID AIR FRACTIONATION 
EFFICIENCY OF PACKINGS 

VERTICAL TOWER 
TOTAL REFLUX 
ATMOSPHERIC PRESSURE 


TOWER I D 

STEDMAN PACKING 2.08" 

ALL OTHER PACKINGS 1.96" 


NUMBERS AT CURVES INDICATE PACKED HT 


CARDING TEETH. 18" 


to 

Ui 
X 

o 

* 5 


UJ 

x 


METAL TEXTILE PACKING, II 3/4” 
-O- 



1/2"GLASS RINGS, 18" 
—-1-Q 


1/4" ALUMINUM LESSING RINGS,I8‘ 



- - 

,□-<-120 X 120 MESH 


1/4" GLASS RINGS,18" 

AESH SJEDMAN I0_3/8a _ _ - — £ -- __ 

60X40 MESH STEDMAN, 10 Z/f 


STEDMAN, 10 3/8" Q 
100X100 MESH STEDMAN 10 “ “ 


'80 X 80 MESH STEDMAN,9 3/4" 


500 1000 1500 2000 

LIQUID RATE TOP OF TOWER , LB/HR FT 2 


2500 


Figure 15. Packing efficiencies. 














































154 


LIQUID AIR FRACTIONATION 


10 

9 

8 

7 

V) 

£ 6 

o 

z 

- 5 

CL 

U 4 

X 

3 

2 


PACKED 

SYM80L HT RUN NO 

B 1/4" BERL SADDLES 18“ 13-17,46 

S BRASS SHOE EYELETS 18" 60-62 

G 1/4" GLASS RINGS I8f' 52-55,79-81 

C CARDING TEETH 18“ III -116 

jt 4-8 MESH HAYOITE 18“ 29,50 

(H) 3/8“ HAYDITE 18“ 41,42 

R REGENERATOR PACKING 18“ 47,49 

X SINGLE TURN GLASS 16“ 82,83 

Y 


•< WIRE 

18 

__-—c 

c 














c/ 

Xc A 






R 

B \/ 





b^ rr 

“ W\o 





























500 1000 1500 2000 2500 

LIQUID RATE , TOP OF TOWER, LB/HR FT 2 


3000 


Figure 16. Packing efficiencies. 


greatly affected. This might indicate that the capa¬ 
city is not altered hy the inclination. 


Description of Packings Tested 

The following is a description of the packings in 
the order in which they appear in Table 1, a few 
of which are shown in Figure 22. 

Berl Saddles. This is a saddle-shaped packing, 


manufactured hy Maurice A. Knight, Akron, Ohio. 
Only /4~in. size semi-porcelain saddles were tested. 
This packing was tested first because it has the repu¬ 
tation of being one of the most efficient of all tower 
packings. All tests with it were made before the 
importance of the verticality was discovered. The fact 
that the Collins-McMahon 4-in. diameter column 
packed with saddles performs better than the 2-in. 
Yale column suggests that the latter tower was not 
vertical when tested. 

Carding Teeth, Wire and Glass Helices. These 
packings were first studied in small laboratory col¬ 
umns. They were found to he rather efficient, having 
HETP’s as low as 2 in. with the system heptane- 
methyl cyclohexane. It is reported also that the 
HETP’s vary over a threefold range, depending upon 
the wetted condition of the packing. 

Carding teeth are similar to rectangular hairpins. 
The particular hatch tested contained teeth about 
yi in. wide and ]/\ in. to Yi in. long. The single-turn 
helices are exactly what the name implies, a wire 
helix of one turn. 

The carding teeth were tested in a vertical col¬ 
umn ; the tests with helices may or may not have 
been in a vertical tower. When tested in a tower not 
known to he vertical, all three of these types showed 
HETP’s which increased with throughput. Outside 
of a similar slight tendency in the 120-mesh Stedman 
packing, these are the only instances encountered in 


10 

9 

8 

7 

o 

cj 6 
x 

2 5 
- 4 


Ol 
O 
oe 
o 

u 

<r 

to 

to 

IL) 

cc 

CL 






4 

i- 


i ii 1 | 







4 


//r 

— FLOOD POINT, X 









/°4 

1 1 1 








! v 

it 

FLOOD POINT,A 








'/i 

y 1 1 i 

MESH PACKED HT Rl 

JN NO 






• 

/ 

X 60X60 10 3/4" 132-134,136,137 

O 80X80 9 3/4" 138-140.153-163 





p 

//I 
//p 


A 1C 

□ 12 

v 1 / 

)0XI00 10 3/8" 125 

10X120 10 3/8" 129 

INDICATES FLOODING 

OLUMN VERTICAL, 2.08" 1 
OTAL REFLUX 

-128 

-131 






7//1 

V 


-?c 

c 

7 

D 




0 

r 

\ 


ATMOS 

VAPOR 

LIQUID 

PHERIC 

DENSITY 

DENSITY 

pres; 
r = 0.2 

f - 50 

SURE 

9 LB/C 
0 LB/ C 

U FT 
UF T 



100 


200 300 400 600 800 1000 

VAPOR RATE,TOP OF TOWER,LB/HR FT 


2000 3000 4000 6000 8000 

2 


Figure 17. Relation between pressure drop and vapor rate for Stedman packing. 

































































EXPERIMENTAL PROGRAM 


155 



100 


200 


300 400 


600 800 1000 


2000 3000 4000 6000 8000 


VAPOR RATE, LB/HR FT , TOP OF TOWER 


Figure 18. Relation between pressure drop and vapor rate for various packings. 


which the packing efficiency was adversely affected 
hy increased throughputs. In a vertical tower the 
HETP of carding teeth was apparently independent 
of throughput, having a constant value of 7.4 in. The 
HETP's of the helices varied between 3 in. and 6 in. 

Carding teeth have the second highest capacity of 
all packings tested, 2,520 lb per hr per sq ft of liquid 
at total reflux. The helices have about the same 
capacity as 34-in. Berl saddles, 1,500 lb per hr per 
sq ft. 

Ewell Packing. This is a close pitch screen spiral 


wound around a rod and inserted in a column. The 
size tested had a core and was. fitted in a 1-in. 

diameter tube. The capacity was so low (350 lb per 
hr per sq ft) that it was impossible to operate the 
apparatus. No efficiency data were obtained. Because 
a packing of such low capacity was of no use, no 
further tests were made. 

Fibcrglas. Three different kinds of Fiberglas were 
tested, one of these at three different packed densities. 
The tower inclination was not measured. As ex¬ 
pected, the lowest density material hadsthe highest 






















































































156 


LIQUID AIR FRACTIONATION 



100 200 300 400 600 800 1000 2000 3000 

VAPOR RATE LB/ HR FT 2 TOP OF TOWER 

Figure 19. Relation between pressure drop and vapor rate for glass rings. 


capacity. With Fiberglas No. 1 the capacity dropped 
from 1,920 to 1,510 lb per hr per sq ft when the den¬ 
sity was increased from 0.72 to 1.79 lb per cu ft. 
The best HETP obtained was 6.9 in. 

Haydite. This material is an expanded shale ag¬ 
gregate produced by roasting and grading the natu¬ 
ral shale. Haydite is manufactured by the Cooksville 
Company, Toronto, Canada. The packing may be 
obtained in various sizes. For the finer material, 
HETP's of 1.5 to 2.0 in. were reported with ben¬ 
zene-carbon tetrachloride mixtures, and an HETP 


of 0.8 in. was reported with oxygen isotopes water 
mixtures. 

The two sizes used in the tests were 4 to 8 mesh 
and 24 in. to 34 in. The packed density was 2.5 lb 
per cu ft and the voids were 55% to 58% of the total 
volume. These values hold for both size ranges. The 
surface area estimated by the manufacturer is 1,600 
sq ft per cu ft for the smaller size and 280 sq ft per 
cu ft for the to 34-in. size. 

These tests were made in towers of unknown ver¬ 
tically. The finer size range was retested in a verti- 









































































EXPERIMENTAL PROGRAM 


157 


PACKING TYPE 

STEOMAN PACKING, 60 X 40 MESH 
STEDMAN PACKING, 80 X 80 MESH 
STEOMAN PACKING, 100 X 100 MESH 
GLASS RASCHIG RINGS, 1/4" - 10“ DEPTH 
GLASS RASCHIG RINGS, 1/4“ - 18“ DEPTH 
STEDMAN PACKING,120 X 120 MESH 
LESSING RINGS, 1/4“ X 1/4“ ALUMINUM 
SHOE EYELETS 
HAYDITE, 4- 8 MESH 
BERL SADDLES, 1/4* X 1/4“ 

HELICES, GLASS 1/8“ SINGLE TURN 
GLASS RASCHIG RINGS 1/2” 

HAYDITE, 3/8“ - 1/2“ 

REGENERATOR PACKING 

METAL TEXTILE 

HELICES, WIRE 3/32 SINGLE TURN 
FIBERGLAS, 10.7 LB /CUBIC FOOT 
FIBERGLAS, 1.79 LB /CUBIC FOOT 
FIBERGLAS. 4.3 LB /CUBIC FOOT 

CARDING TEETH 

FIBERGLAS, 21.4 LB /CUBIC FOOT 
FIBERGLAS,0.72 LB /CUBIC FOOT 
EWELL PACKING, l“ DIAMETER 


PACKING CAPACITY 

LIQUID TRAFFIC IN TOP OF 
TOWER AT TOTAL REFLUX 

PACKING HEIGHT 

EQUIVALENT TO A 
THEORETICAL PLATE 

L 

H 



1 




i 

a 







i 




l 




i 




1 




1 




i 




l 




1 




1 




1 




1 




i 

im 



1 




I 






1 




■iiii 


1 


c 

1 1 i 1 

2500 2000 1500 1000 500 

LB /HR 'SO FT 

5 2 4 6 e 

INCHES 


10 


Figure 20. Summary of efficiencies and capacities of various packings. 


















































158 


LIQUID AIR FRACTIONATION 




INCLINATION OF TOWER, DEGREES 

Figure 21. Effect of verticality of tower on efficiency and pressure drop. 


cal tower. In this latter series of runs the tower was 
operated above total reflux so that it was not possible 
to compute the HETP. No capacity measurements 
were made in the vertical tower. 

In the Yale tests 4- to 8-mesh Haydite and % -in. 
Berl saddles gave about the same efficiency, both 
having a minimum HETP of 2.7 in. The best HETP 
of the coarse packing was 4.4 in. 


The capacity of the packing may be limited by 
either actual flooding of the packing or by the lifting 
velocity of the particles. The particles, being porous, 
have the apparent specific gravity of 0.7. In the first 
tests with the 4- to 8-mesh size, one-third of the pack¬ 
ing in the tower was blown overhead at a load of 
1,250 lb per hr per sq ft. If the lifting velocity is less 
than the actual flooding velocity, it is necessary to 

































































EXPERIMENTAL PROGRAM 


159 


retain the packing between screens. The actual lift¬ 
ing velocity in liquid air fractionation has not been 
determined for any size of packing, but in view of the 
light weight of Haydite it would seem a wise precau¬ 
tion to place some sort of a barrier above it. 





< <$■ V C; 


r~ : 


L 


0 / 

c 


2 INCH 

REGENERATOR 


l/ 4 INCH 
BERL SADDLES 



wS 


3/g INCH 
HAYDITE 


2 INCH 
STEDMAN 



6-8 MESH 
HAYDITE 


Figure 22. Various tower packings. 


When tested in the Pennsylvania State Col¬ 
lege tower, the efficiency of the fine packing was 
about twice that of the Z^-in. hterl saddles. This may 
mean either that the performance of Haydite is less 
influenced by the tower diameter, or that the tests in 
the small tower are in error because of the unknown 
inclination. The capacities measured in the two 
towers are in agreement. 

Regenerator Packing. This packing consisted of a 
2-in. diameter coil of the crimped aluminum strip 
used in the regenerative heat exchangers. The strip 


was 2 % 2 in. wide with an uncrimped thickness of 
0.013 in. The thickness of the crimped strip was 
0.045 in., the pitch and angle of crimp were 0.174 in. 
and 45 degrees respectively. Two strips with the 
crimping opposed were wound together to make up 
the coil. The estimated surface area was about 600 
sq ft per cu ft, while the packed density was 54 lb 
per cu ft. 

This packing behaves as if it were a bundle of small 
wetted wall columns, that is, there is no tendency of 
the packing to redistribute the liquid after the initial 
distribution. 

The tower was tested twice, the first time with 
unknown verticality. In these tests the lowest HETP 
was 4.7 in. at the flooding point. The tower was 
retested in a vertical position, but since it was oper¬ 
ated with a high oxygen drawoff it is impossible to 
compute the HETP. The capacity was not rede¬ 
termined. 

Lessing Rings. This packing is much like a Raschig 
ring; the only difference is an addition of an axial 
partition the entire length of the ring. The packing 
was tested in a vertical tower. The efficiency varied 
only 30% over a fourfold range of feed rates. The 
best HETP was 2.0 in. at the flooding rate of 1,550 
lb per hr per sq ft at total reflux. This ring system 
was one of the best packings tested. 

Glass Y^%-in. Raschig Rings. Tests made in a 
vertical tower with this packing produced some ex¬ 
tremely interesting results. Two different depths of 
packing, 10 in. and 18 in., were used. The results, 
which are plotted in Figure 15, show the shorter 
length to be the more efficient and to have the lower 
capacity. The agreement between the HETP for 
the two heights is slightly better when plotted as a 
function of pressure drop than as a function of the 
liquid or vapor traffic in the top of the tower. The 
pressure drops per foot of packing at the flooding 
point were equal, hut the capacity of the 10-in. sec¬ 
tion was only 80% of the capacity of the 18-in. depth. 
The HETP of 1.6 in. and 1.9 in. at the flooding 
points were better than those obtained with any other 
bulk packing. 

The differences in the efficiencies may have been 
the result of either the effect of height upon the liquid 
distribution, or an actual difference between the na¬ 
ture of the packing in the two tests. The variation 
in the capacity indicates that possibly the 18-in. depth 
was more loosely packed. The packed densities were 
not measured. 

Following these peculiar results, further tests were 




160 


LIQUID AIR FRACTIONATION 


made with packed depths of 18 in., 32 in. and 48 in. 
The results are plotted in Figure 23. Because of the 
effectiveness of these heights it was necessary to use 
relatively high oxygen drawoffs to avoid the analyti¬ 
cal errors arising from extremely high purities ob¬ 
tained at total reflux. Owing to uncertainties in the 
feed composition, HETP’s have not been computed 
for these runs. Instead, the results are presented in 
the form of oxygen purity as a function of the draw¬ 
off rate. 

Figure 23 shows the amazing fact that the 32-in. 
depth actually performs better than the 48-in. depth, 


which is 50% longer. Although the shorter section 
might be expected to be more efficient per unit length 
than the longer, it certainly does not seem reasonable 
that additional length could possibly decrease the 
fractionating ability of a tower. It therefore seems 
reasonable to assume that the packing in the 32-in. 
depth was so arranged that it was more effective. 
This is substantiated by the fact that the pressure 
drops in the 32-in. section were higher than in the 
48-in. column. This should not be taken necessarily 
to mean that liquid distribution is greatly affected by 
the packed height. 



100 MOLES 0 2 LVG TOWER 

Figure 23. Effect of packed height on tower performance. 



















































EXPERIMENTAL PROGRAM 


161 


Distribution of Liquid 

Tests were made for liquid redistribution in the 
48-in. tower. Two types of redistributors were tested, 
one which directed the liquid to the center of the 
tower, and the other type which sent the liquid to 
the tower wall. Normally, in towers operating above 
room temperatures, the liquid tends to move toward 
the wall, but in the case of liquid air it was thought 
that perhaps heat leak would tend to dry the packing 
at the walls, and that therefore redistribution should 
be made toward the outside of the tower. These tests 
were made in a vacuum-jacketed column in which 
the heat leak was about half that of the Santocel 
insulated unit used for the 18-in. tower tests. 

The tests with the two distributors are those out¬ 
lined with the double circle in Figure 23. If there 
is any effect of these redistributions it is an adverse 
one. 

One-half Inch Size. A few tests were made with 
this larger size of glass ring packing. The maximum 
capacity was 2,300 lb per hr per sq ft, but the best 
HETP was only 4.2 in. The high capacity of these 
rings relative to the J4~in. size suggests that the ad¬ 
verse effect of diameter on HETP might be partially 
overcome by their use. In other words, it is possible 
that to do a given job a tower might be as efficient 
when packed with the larger rings, because the higher 
capacity would permit a smaller diameter tower to be 
used. 

Shoe Eyelets. The eyelets tested were % 2 in- long, 
made of 0.007-in. brass stock, and had a packed den¬ 
sity of 55 lb per cu ft. The chief advantage of the 
packing is that the heat capacity is low compared to 
that of ceramic rings or saddles. The starting time 
of a unit is thus decreased by their use. 

The eyelets show about the same efficiency as 
Lessing rings, having a minimum HETP of 2.0 in. 
The capacity at total reflux is 1,630 lb per hr per sq ft. 

Stedman Packing. Two general forms of this ma¬ 
terial are available, the conical type, made for use in 
very small laboratory columns, and the triangular 
pyramid type. Only the latter type has been tested 
in the research project. 

The HETP data are summarized in Figure 24. In 
the vertical setup, tests were made with four 2.08-in. 
ID towers, each differing in the mesh of the screen 
used. These were 60x40, 80x80, 100x100 and 120x 
120. The efficiency and capacity decrease with de¬ 
creasing mesh openings, as shown in Figures 17 and 
24. The efficiency of each of these is, within experi¬ 
mental error, substantially independent of the 


throughput. The first three sizes are very close in 
performance; the HETP reported varied only from 
1.15 in. to 1.45 in., while the finest mesh has an 
HETP as high as 2 in. In addition, the capacities 
of the first three range from 1,400 to 1,700 lb per hr 
per sq ft while the 120xl20-mesh size floods at 800 
lb per hr per sq ft. Although the superiority is slight, 
the 60x40-mesh packing is the best. 

The larger tower tests showed the importance of 
completely wetting the packing by a preliminary 
flooding. Also, it had been suggested that heat leak 
tended to oppose the wetting by evaporating liquid 
from the outside of the packing layers. An interest¬ 
ing series of runs were made to show the influence 
of wetting and heat leak upon performance. 11 A hol¬ 
low jacket was placed around the column and the 
li)4-in. annular space between the tower and the 
jacket was filled with insulation. When filled with 
air, the jacket acted as a heat leak shield. The insula¬ 
tion between the jacket and the column eliminated 
excessive heat transfer between the two. The packing 
was wetted by filling the tower with liquid. 

The results of these tests may be summarized as 
follows. 

1. At high feed rates, that is greater than 1,000 
lb per (hr) (sq ft) there is no difference between the 
flooded and shielded, and the flooded but not shielded 
packings. Without shielding or flooding the HETP 
is 30% worse. 

2. At low feed rates, that is, about 500 lb per (hr) 
(sq ft), the performance was as given below: 


Type of Operation HETP Inches 

Flooding and shielding 1.05 

Flooding only 1.15 

Shielding only 1.3 

Neither flooding nor shielding 1.65 


The whole range of HETP variation is only half 
an inch at the low rates, but this is 50% of the lowest 
HETP. 

These data should not be applied quantitatively 
to columns of different diameter, because the effect 
of heat leak should diminish as the tower diameter 
increases. 

Metal Textile Packing. This packing consisted of 
woven metal cloth rolled into cylinders which were 
stacked above one another in the tower. The wire 
diameter was 0.006 in. and the packed density 17 
lb per cu ft. 

This packing had the highest capacity of any tested 
[2,600 lb per (hr) (sq ft)], but the HETP of 6 in. 
is decidedly poor. 



H E TP INCHES 


162 


LIQUID AIR FRACTIONATION 



MESH 

PACKED HEIGHT 


RUN 

NOS 

® 

60X40 

18" 

COLUMN CAREFULLY CENTERED 

118 

- 120 

X 

60X40 

10 3/4" 

ANGLE OF INCLINATION = 0° 

132 

- 134,137 

O 

80X80 

9 3/4" 

ANGLE OF INCLINATION = 0° 

138 

- 140 

A 

100X100 

10 3/8" 

CAREFULLY CENTERED ON GUIDES 

121 

- 123 

A 

100X100 

10 3/8" 

ANGLE OF INCLINATION = 0° 

125 

- 12 8 

□ 

120X120 

10 3/8" 

ANGLE OF INCLINATI ON = 0° 

129 

-13 1 


INCLINATION NOT KNOWN FOR FIRST AND SECOND TESTS 





SECON 

RUNS 

MESI 

D TEST 60 X 
75 -78 

4 HT 

40 18 

/ 

, > 

^ \ 

/ \ 

/ \ 
/ N 





/ 

/ 

/ 

/ 

/ FIRST 

-/- 

RUNS 93 - NO 

MESH 

TESTS (80 X 80 
(100 X 100 
(120X120 

HT \ 

II" 

FIRST TE 
± RUNS 31 

MESH HT 

ST 60X40 18 

-38 

I 

/ 

/ 

/ 

) 

) ^0 
s' 

s' 

* 





X' 

/ 







--tA- 




_—irx. 

__ 










0 500 1000 1500 2000 2500 

LIQUID RATE , TOP OF TOWER , LB / HR FT 2 


Figure 24. Stedman packing performance. 

































EXPERIMENTAL PROGRAM 


163 


LIQUID AIR FEED Q 

7 



COMPRESSOR 


EXHAUST 


LEGEND 

TEMPERATURE, F 
RPM 

GAS FLOW RATE, SCFH 
Ofr ANALYSIS, % 0 2 
LB/ HR 

IN. OF LIQUID LEVEL 
7 EXHAUST O PRESSURE, LB/SQ INGA 
^ DEW POINT, F 

IN. OF WATER PRESSURE 


Figure 25. Experimental setup for large towers. 


8 7 2 Large Column Tests 

A flow sheet of the large scale testing equipment 
is shown in Figure 25. The unit was similar to a low- 
pressure oxygen plant except for the difference in its 
source of refrigeration. 11 Here refrigeration was sup¬ 
plied by the injection of liquid air into the exhaust 
gas side of the heat exchangers. Consequently the 
control and operation of the tower approximated 
those of an actual unit. 

Berl Saddle Packing 

The tower (Figure 26) used with Berl saddles as 
bulk packing was the first of the full-size towers to 
be tested. It was designed and built at approximately 
the same time as the tower for the M-2 unit. The 
packed height and diameter of the test tower were 
chosen so that experimental data would be directly 
applicable to the design of fractionation equipment 
for the M-2 and other portable units. The tower 
diameter below the vapor feed point is less than that 
above in order that the best possible efficiency might 
be attained in each section by operation at the high¬ 
est permissible liquid and vapor rates. The first pack¬ 
ing to be tested was %-in. Berl saddles, as Yale tests 



Figure 26. Details of packed test tower. 












































































































































































































164 


LIQUID AIR FRACTIONATION 


showed this to be the most efficient of those under 
consideration. 

A series of single liquid feed runs at varying 
throughputs and oxygen production rates were made. 
The total packed height in these runs was 58 in. 
Figure 27 illustrates the results, giving the smoothed 
curves for varying throughputs. As expected, the 
packing efficiency increases with the feed rate. 



Figure 27. Relation between air feed and oxygen re¬ 
covery and purity. 


In order to obtain good efficiency data, an addi¬ 
tional series of runs was made with a constant oxygen 
recovery of 25% at feed rates from 5,000 cfh to the 
flood point, which was about 8,500 cfh. The data so 
obtained show that the HETP varies inversely as the 
0.6 power of the feed rate. 

The efficiency of the saddles, judged by these runs, 
was very poor. The best HETP was slightly less 
than 6 in., or about three times the best value found 
in the small Yale column. This large, adverse effect 


of diameter was much worse than had been antici¬ 
pated. The decreased efficiency was probably caused 
by poor liquid distribution and the consequent need 
for redistribution. This is not an easy problem to 
solve in a short tower. The best redistributors all 
involve some method of collecting liquid out of con¬ 
tact with the vapor and then redistributing it. Since 
packing height is sacrificed by this redistribution, it 
is possible that with the low packed height allowable 
any increase in efficiency thus gained might be offset 
by the decreased amount of packing. 

Following the single tower experiments, a series 
of runs was made using the low-pressure vapor feed 
to increase the oxygen recovery. A summary is 
shown by the curves in Figure 28. These show star¬ 
tlingly how the simple single tower yield may be 
raised through the use of vapor feed. 

Stedman Packing 

Long before the tests with saddles were finished it 
was evident that a much more efficient tower must 
be developed if the process specifications for portable 
units were to be met. Two towers, therefore, were 
designed, and their construction ordered—a Sted- 
man-packed tower and a tray column. 

Published Stedman packing performance with 
benzene-ethylene-dichloride mixtures showed only a 
25% decrease in efficiency in 6-in. diameter packing 
versus 2-in. diameter packing. On the basis of the 
small column tests, a 6-in. diameter tower was large 
enough to be used in portable units. Although in the 
Yale tests Berl saddles were about twice as efficient 
as Stedman packing, it appeared that in a larger tower 



Figure 28. Effect of vapor feed on oxygen recovery and purity. 































































EXPERIMENTAL PROGRAM 


165 


the latter might be better because of the much smaller 
effect of diameter. On this basis a tower with a total 
of 3 ft 9 in. packed space was ordered and tested. 

After the first few runs as a single-feed tower it 
was discovered that if the packing were completely 
wetted by filling the entire tower with liquid air the 
efficiency was improved, in fact almost doubled. This 
peculiarity of Stedman packing has been the subject 
of a great deal of conjecture. There is a question as 


To call the performance of Stedman packing er¬ 
ratic is not to imply that the material is unsatisfactory. 
On the contrary, the average HETP of 3 in. for this 
packing is easily half that of the Berl saddles. Al¬ 
though the deviation from the average is as much as 
50%, the maximum HETP is still substantially less 
than the best value for Berl saddles. This is shown 
graphically by Figure 29, in which all the single liquid 
feed runs are given. There seems to be no noticeable 



>• o- 

0 1 2 3 4 5 6 7 8 9 10 II 12 13 14 

PRODUCT YIELD SCF PRODUCT PER 100 SCF FEED 

Figure 29. Stedman 6.08-in. diameter tower performance. 


to whether or not at any given feed rate the screen 
might eventually become entirely wetted and the bet¬ 
ter efficiency thus obtained in the course of normal 
operation. Conversely, if the tower is flooded with 
liquid before operation begins, the possibility exists 
that the packing might become unwetted and the 
fractionation efficiency impaired. That either or both 
of these effects occur to some degree is shown by the 
general erratic performance of Stedman packing. 


effect of feed rate upon the efficiency. This is unlike 
the behavior of bulk packing. Perhaps the reason for 
this is that the major effect of increased liquid and 
vapor loads is to extend the wetted surface of other 
packings, but since the surface of the Stedman pack¬ 
ing is already presumably wetted by preliminary 
flooding, no further increase in its transfer surface 
is possible. 

The tests that had been made were sufficient to 






































166 


LIQUID AIR FRACTIONATION 


show that with Steelman packing there was a very 
good chance of meeting the production requirements 
of the portable units. 

Haydite Packing 

The results of a few runs made with 4- to 6-mesh 
size Haydite packing in the original Pennsylvania 
State College test tower are shown by Figure 30. At 
the same liquid and vapor loads the Haydite packing 
is more efficient than the saddles, but has only 70% 
of the capacity of ^4-in. saddle packing. The effect of 
tower diameter appears to be less than in the case of 
saddles. 



0 1 2 3 4 5 6 7 8 9 10 II 12 13 14 

PRODUCT DRAWOFF SCF PER 100 SCF FEEO 

Figure 30. Packed tower performance. 


The characteristics of Haydite packing in this 
mesh size are not good enough to compete with either 
Stedman packing or tray towers. Other mesh sizes 
might be tried, but it is likely that smaller size would 
give greater efficiency with reduced capacity. It is 
possible that Haydite might be useful in rocking 
towers and in large columns because of the apparent 
small effect of diameter. 

Tray Towers 

Independent Engineering Company Tower. This 
tower, 12 in. in diameter, composed of 15 sections of 
two trays each containing a large number of small 
bubble caps, was purchased from the Independent 
Engineering Company, O’Fallon, Illinois. The sec¬ 


tions were the standard production model used in 
the mobile units manufactured by Independent. 1 

The purpose of this test was to compare this tray 
with the tray of entirely different design which was 
being developed by NDRC. Results with this tower 
were not so satisfactory as desired for specific NDRC 
purposes. 

M. W. Kellogg Tray Tower. Of all the towers 
tested in the full-scale size this is the most satisfactory 
from the standpoint of ease and dependability of 
operation, as well as efficiency and capacity. The 
tower is shown in Figure 31 and the trays in Figure 
32. 



Figure 31. Details of tests in plant tower. 


Because there were more theoretical trays in this 
tower than in any other yet tested, the data obtained 
represent the best appraisal of single-tower and the 
vapor feed systems. But, because of the high purities 
and yields, it was impossible to calculate accurately 
the tray efficiencies. 

The effect of the vapor feed location was deter¬ 
mined by using each of three inlet nozzles. These 
were placed below the second, fourth, and sixth 
trays, and behind the downflow so that the entering 











































































EXPERIMENTAL PROGRAM 


167 



SECTION THRU TRAY ASSEMBLY 
SECTION A-A 


Figure 32. Type C tray details. 

























































































































































































168 


LIQUID AIR FRACTIONATION 


vapor would disturb the liquid on the tray as little as 
possible. The data show that the lowest feed location 
is the best and the top one the poorest. It is possible 
that an even lower point of entry would give better 
performance. 

The smoothed performance data are plotted (Fig¬ 
ure 33) to show the effect of the relative amount of 
vapor and liquid feeds upon the oxygen yield for 
various parameters of oxygen purity. In the graph 
the data have been represented by straight lines. 
Those in the upper portion of the chart should curve 
upwards as the yield approaches zero, and as the 
ratio vapor feed/liquid feed becomes very large. 


Short Tray Tower Tests 
The success of the tray tower aroused interest in 
the further development of this sort of fractionation 
equipment. This involved the accurate measurement 
of the efficiency and capacity of all trays tested. For 
this purpose a tower with but four trays was used. 
When operated at total reflux the uncertainties in 
equilibrium data exert the least influence, and if the 
tower is short enough, the product purity is kept in 
the region in which there is a relatively large composi¬ 
tion change over each theoretical tray, thus re¬ 
ducing the error caused by inaccurate product analy¬ 
sis. Another advantage of using total reflux is that 



0 I 2 3 4 5 6 7 8 9 10 II 12 13 14 

OXYGEN PRODUCT YIELD, CF/ 100 CF TOTAL AIR FEED 

Figure 33. Relation between vapor feed and oxygen purity and yield. 


Figure 34 shows the actual data in the form of 
oxygen yield vs oxygen purity curves for various 
constant relative quantities of vapor feed. The vapor- 
feed point was here below the second tray. These 
curves show the sharp break point that is typical of 
towers with a large number of trays; that is, the 
purity is substantially independent of drawoff until 
a certain drawoff is reached, after which the purity 
shows an extreme sensitivity to the production. 


unknown overhead entrainment does not effect the 
calculated tray efficiency. 

Type C-2 Tray 

This is the 2-in. spacing, 12-in. diameter, M. W. 
Kellogg tray with five cap sides blanked off per tray, 
used below the vapor feed in the larger test tower. 
To facilitate construction the shell design was dif¬ 
ferent from the tray shown in Figure 32, but all 








































EXPERIMENTAL PROGRAM 


169 


dimensions are the same. The tray characteristics 
may be summarized as follows. 

Efficiency. The overall tray efficiency is 84% at a 
3,000 scfh feed rate, falls gradually to 75% at a feed 
of 11,000 scfh and drops sharply to 60% at 12,000 
scfh. 

Capacity. This seems to be a tray in which the 
capacity is set by the tray efficiency; even at a feed 
rate of 13,000 scfh the analysis of the flood point 
sample line does not indicate flooding. The effective 
capacity of this tray may be taken as 10,000 to 10,500 
scfh, or in terms of the vapor and liquid loads, 
Z = 23.5 at a liquid rate of 95 gal per hr. 


Capacity. This is a tray in which the capacity is 
determined by the flooding point. The overhead 
entrainment, pressure drop, and the flood point sam¬ 
ple analysis all indicate that the capacity is reached 
at a feed rate of 8,000 scfh. The liquid and vapor 
loads at this point are Z = 17 at a liquid rate of 75 gal 
per hr. This flooding rate, determined with liquid 
air, agrees almost exactly with the capacity predicted 
by the air-water tests on these trays. 

West Trays 

The tray design, shown in Figure 35, represents 
an effort to attain higher overall efficiencies through 



O 5 10 15 20 

OXGEN YIELD CF PER IOO CF LIQUID FEED 

Figure 34. Performance of tray tower. 


Type D Tray 

The type D tray is similar in design to the type C 
except that the spacing is 1% in. The tray was laid 
out on the drafting board by cutting dimensions 
wherever possible. After fabrication the trays were 
tested briefly with air and water to establish the 
capacity. The characteristics of this tray may be sum¬ 
marized as follows. 

Efficiency. The efficiency of the tray is practically 
independent of the throughput at feed rates of 3,000 
scfh and greater. At throughputs lower than this the 
efficiency falls off because the slots are not all active. 
The overall efficiency obtained by averaging all the 
runs is 76%. This is about 5% less than that of the 
2-in. spaced tray, but as the tray spacing is 25% less, 
the net increase in the efficiency of height utilization is 
20 %. 


a cross-flow effect. This cross-flow effect is obtained 
in a rather unusual way. The plate is divided in half, 
liquid flows along one side, around a U bend, and 
back the other side into a slanting downflow which 
delivers the liquid to the next tray. All the points 
of liquid entry are in a vertical line. This liquid sys¬ 
tem has been termed co-ordinated reflux. There is 
a vertical strip rising from the center of the tray 
above. The purpose of this strip is to prevent the 
vapor rising from one side of the tray from mixing 
with the vapor rising from the other side. Another 
feature of the tray is the perforated plate lying above 
the top of the slots of the bubble cap. This is claimed 
to be important in increasing the efficiency, but the 
perforated area was found to be too large to be en¬ 
tirely effective in the present application. 

In performance the West tray was rather dis- 



































170 


LIQUID AIR FRACTIONATION 


CO 

m 

o 


o 

2 

-< 

-< 






■ v” 



^- 


SECTION W-W 


Figure 35. Details of West tray. 

















































































































































































EXPERIMENTAL PROGRAM 


171 


appointing in view of the favorable theoretical possi¬ 
bilities. It should be noted, however, that because 
of the complicated construction the perforated plates 
were warped, and there was a gap between the plates 
and the shell. There were also other slight devia¬ 
tions from the recommended design dimensions. It 
is quite possible that the warped perforated plate did 
inhibit the cross-flow eft’ect. The performance is sum¬ 
marized as follows. 

Efficiency. The overall tray efficiency is about the 
same as that of either the type C or D tray. The value 
of 78% at a feed rate of 3,000 scfh drops gradually 
to 72% at 6,000 scfh. 

Capacity. As indicated by entrainment and the 
break in the flood point analysis curve, the tray floods 
at a feed rate of 6,000 scfh. The reason for the low 
capacity compared to the type C tray is that in the 
West tray the liquid path is twice the length and half 
the width of that in the type C tray. This undoubt¬ 
edly causes a larger liquid gradient and consequent 
lower capacity. 

As the capacity of the West tray was much less 
than the type of tray and the efficiencies were about 
the same, there did not seem to he much point in con¬ 
tinuing work on the West tray. However, since 
there is some doubt that the design was given the 
best possible tests, and because the co-ordinated re¬ 
flux principle is a sound attempt to take advantage 
of the cross-flow effect, further development might 
be advisable. 

8 - 7 - 3 Rocking Column Tests 

Because of the shipboard applications of fractiona¬ 
tion columns, it is necessary to have some knowledge 
of the behavior of packed and tray towers when sub¬ 
jected to the motion encountered at sea. For such a 
study the entire test unit was mounted on a platform 
on which the motion of a ship could be simulated by 
an ingenious arrangement of cams, rocker arms and 
gimbals. The unit was so designed that a 5-degree 
tilt from the vertical was obtainable in one direction 
and a 15-degree tilt in a direction at right angles to 
the first. These directions were designated by the 
terms pitch and roll, respectively. 11 ’ 21 

In the pitch direction, the axis of motion was 
below the tower and perhaps 2 ft away, while the 
axis of rocking motion passed through the tower 
somewhat below the midpoint. The form of the 
pitching and rocking motion has not been described, 
other than to state the number of cycles per minute 


and the maximum angle, that is, the variations in the 
angular velocity throughout a cycle are not reported. 
An exact description of the tower motion in terms 
of the three spatial co-ordinates and time is a diffi¬ 
cult task. There is probably, however, some optimum 
location for a tower with respect to the natural axes 
of a ship. 

Stedman Tower 

The original 6-in. diameter Stedman tower was 
the first unit tested under a rocking motion. The 
experimental work on the new platform included 
also stationary tests with the tower in both vertical 
and inclined positions. All tests were made at a con¬ 
stant feed rate of 6,000 scfh. The yield was always 
50% or less, to avoid the errors of computing 
HETP’s at high recoveries. Typical results are given 
in Figure 36, which shows the variation of HETP 
with column motion. 

When vertical and stationary the tower perform¬ 
ance fell within the same range reported for the pre¬ 
vious tests. When tilted, but stationary, the efficiency 
dropped badly as had been predicted by the Yale 
tests. The HETP reached a value of 20 in. for a 
5-degree tilt. The tower was so sensitive to the ver- 
ticality that it was possible to find the perpendicular 
position by following the oxygen analysis as well as 
by the use of spirit levels. 

To test the symmetry of the unit the tower was 
inclined in various directions while stationary. Dif¬ 
ferences in the packing efficiency in the various tilt¬ 
ing directions are certainly within the range of repro¬ 
ducibility of Stedman packing efficiency. If there is 
a real effect of tilting direction, it might be caused by 
slight non-uniformities in the tower packing itself. 

In the rocking experiments only two angles were 
used, 3j4 degrees from the vertical, pitching, and 13 
degrees from the vertical, rolling. The influence of 
motion may be summarized by stating that if the rate 
of motion is greater than four cycles per minute, 
there is very little effect of the angle of inclination 
and the performance is approximately the same as 
when the tower is vertical or direction active, but is 
also true when both motions are active, provided 
that the frequency of either motion is not less than 
4 to 5 cycles per minute. 

The capacity of the tower was not measured when 
rocking or when tilted. It might be predicted that 
the capacity would be less when rocking because of 
the unsteady pressure drop across the packing. The 
variation in the pressure drop has been tabulated. 



20 

19 

18 

17 

16 

15 

14 

13 

12 

I I 

I 0 

9 

8 

7 

6 

5 

4 

3 

2 


LIQUID AIR FRACTIONATION 



Figure 36. Tower performance under rocking conditions. 














































































EXPERIMENTAL PROGRAM 


173 


Four 12-in. Diameter Airco Compartment 
Trays 

For use in rocking towers the Air Reduction Com¬ 
pany proposed a tray which is divided into several 
compartments, each compartment having its own 
downflow, sealpot and bubble caps. 23 - 24 The M-6 
unit, which uses these trays, is intended for eventual 
shipboard service, and because of its size it was im¬ 
possible to test the performance of the full-size tray 
when rocking. Therefore, a four-tray test tower 
with 12-in. diameter trays on a 3j4-in. spacing was 
built and tested. Each tray had fifteen compartments. 
These compartments are shown in Figure 37. 


formly among the compartments on the top tray. 
Therefore, the distributor was designed very care¬ 
fully and was first tested with air and water before 
installation in the test tower. 

When level and stationary the overall tray effi¬ 
ciency was highest at low feed rate, 70% at 4,000 
scfh, falling to 55% at a feed rate of 8,000 scfh, and 
remaining at this value up to the flooding point. In 
terms of the liquid and vapor rates the tower flooded 
at a vapor rate of Z — 28 with a liquid rate of 140 
gal per hr. 1 

When the tower was rocked the efficiency dropped 
slightly. No runs were made below an 8,000 scfh 



SECT B-B 

Figure 37. Details of compartmented (Airco) tray. 


The trays were installed so that the direction of 
the lesser deflection (pitching) was parallel to the 
longer side of the compartments. As the tower is 
essentially a group of parallel columns it is abso¬ 
lutely necessary that the liquid be distributed uni¬ 


feed rate, so it is not known whether the efficiency 
under motion is higher at lower loads. At feed rates 
above 8,000 scfh the efficiency was independent of 
the throughput as in the stationary column. At low 
angular deflections (pitching), the efficiency dropped 











































































































































174 


LIQUID AIR FRACTIONATION 


to 50% at 2 cycles per minute, but only to 52% to 
54% at 6 cycles per minute. The lowest efficiency 
encountered was 42% to 45% with a compound mo¬ 
tion of two pitch and two roll cycles per minute. In 
general, lower angles and higher frequencies resulted 
in the least reductions in efficiency from the station¬ 
ary, vertical value. No tests were made with the 
tower inclined but stationary. 

The capacity of the trays is about the same when 
rocked as when vertical. As a throughput of 15,000 
scfh entrainment appeared in the overhead gas when 
the tower was stationary, but when rocking there 
was no entrainment at this feed rate. The tower 
pressure dropped, however, indicating a flooding 
point of about 15,000 scfh either rocking or sta¬ 
tionary. 

Two 10-in. Diameter Airco Type Trays 

These trays are similar to the trays to be used in 
the M-6 unit above the vapor feed point. Each tray 
has eight Airco compartments; tray spacing is 6 in. 
It was necessary to reduce the tower diameter to 10 
in. so that the required tower loads might be within 
the capacity of the test air supply. 

Since the purpose of the tests was to reproduce 
the conditions in the upper part of the M-6 tower, 
vapor feed was introduced at the bottom of the two- 
tray section while liquid was fed in the normal manner 
to the top. No efficiency data were taken since only 
capacity information was desired. 

At the maximum available air supply of 15,000 
scfh, entrainment appeared in the overhead when the 
tower was stationary and level, but disappeared when 
the tower was rocked. The pressure drop of 1 to 2 
in. of water at this point indicated that the tower 
was not flooded. The loads at the point of entrain¬ 
ment were: vapor rate of Z = 43, and liquid rate of 
85 gal per hr. 

Air Reduction Company Test Towers 

The experimental tower tests made by Air Reduc¬ 
tion Company were for the purpose of developing 
towers suitable for shipboard units and portable 
plants. 22 

The tests made with packed towers were incon¬ 
clusive because the air rates are greater than the 
capacity of the tower. The tests with tray towers 
were part of the necessary groundwork in the devel¬ 
opment of shipboard columns. The information 
shows in general only that the efficiency drops 20% 


to 50% when the trays are rocked. The motion was 
a rocking one in one direction only and the axis was 
beneath the tower. 

The results of tests made with packed towers are 
summarized briefly. 


Packing 


HETP 


*4-in. brass Raschig ring 
%-in. Berl saddles 
y 2 - in. Berl saddles 


4.0 to 4.5 in. 
4.5 to 5.0 in. 
5.3 to 6.0 in. 


These tests led to the installation of a 6-in. ID 
tower having 24 trays in the Air Reduction Com¬ 
pany’s portable unit, as it had been found that a 3 r /8 - 
in. tray spacing gave an 80% efficiency or an HETP 
of 3.9 in. The operation of the tray tower was also 
thought to be more reliable than that of a packed 
tower. 

Experiments with a 14-in. diameter tower, packed 
with 34 -in. porcelain rings, were made to ascertain 
if packing could be used in the M-6 unit. The very 
poor results show the enormous effect of tower diam¬ 
eter on efficiency. The ^-in. porcelain rings had 
been used in the small tower and were reported to be 
“as good as the saddles.’’ 


8 7 4 Fractionating Column for Shipboard 
Operation—the J Tray 

In view of the intended application of oxygen units 
to service on shipboard, it was necessary to develop 
a highly efficient fractionating tower tray for opera¬ 
tion under rocking motion conditions. A tray (Type 
J) 1 ’ 3 was developed, which embodied an attempt at 
high capacity and high tray efficiency under both 
rocking and stationary conditions, with a reasonably 
low tray spacing. 

Details of the tray are shown in Figure 38. Es¬ 
sentially the tray is a 3 in. by 9 in. rectangular sheet 
perforated with Ys-in. holes. The overflow weir is 
2 in. high and a baffle 2 in. high extends across the 
middle of the tray; these features maintain adequate 
submergence of the perforations when the tower is 
tilted. A 1-in. bed of crimped wire cloth is sus¬ 
pended beneath the tray to limit the inter-tray en¬ 
trainment. A 6-in. tray spacing is used. For a 
larger column a number of such units would be set 
side by side in separate compartments. It is in¬ 
tended that the longer axis of each plate be aligned 
parallel to the length of the ship so that this axis 
tilts with the less extreme pitching motion and the 
shorter axis tilts with the rolling motion. 1 - 21 



EXPERIMENTAL PROGRAM 


175 



Performance 

A small tower consisting of four type J trays was 
constructed and tested in the rocking platform appa¬ 
ratus. 11 - 21 The apparatus is similar to a low-pressure 
oxygen plant, with liquid air as the source of re¬ 
frigeration. Dried, CCL-free compressed air at about 


100 psi is cooled to liquefaction temperature in a 
heat exchanger by cold air returning from the frac¬ 
tionating tower and exhausting to the atmosphere. 
The cold compressed air is then totally condensed 
in the reboiler at the bottom of the fractionating 
tower, and the liquid is throttled into the top of the 





















































































































































































176 


LIQUID AIR FRACTIONATION 


tower. A small part (10 to 15%) of the liquid vapor¬ 
izes through the reduction in pressure, and the 
remaining liquid passes down the tower trays coun¬ 
tercurrent to vapors rising from the reboiler. 

The gas from the top of the column is passed 
through a calorimeter in which a measured electric 
heat input can be maintained, and the rise in tem¬ 
perature of the stream determined. Liquid air for 
refrigeration requirements is added to this return 
stream before it enters the exchanger and the ex¬ 
hausts from the system. In addition, any desired 
quantity of vapor can be by-passed around the tower 
trays in order to change the liquid-vapor flow ratio 
through the trays. The entire plant is mounted on a 
platform which can be rocked with separate or com¬ 
bined pitch and roll motions, with each motion inde¬ 
pendently variable in frequency and amplitude. 

Flooding points were established within limits of 
about 5%. The tower becomes flooded at a critical 
vapor load which is independent of liquid load over 
the range studied. Apparently the downcomers are 
sufficiently large that there are practically no friction 
losses due to liquid flow, and if the static pressure 
drop between two successive trays is lower than the 
maximum hydrostatic head available to force liquid 
into the lower tray, adequate liquid flows can be 
handled. The critical vapor load occurs when the 
hydrostatic head and the pressure drop are equal, and 
at higher vapor loads there can be no liquid flow 
whatsoever. 

At a tower pressure of 6 psi, the critical vapor 
load is 5,700 scfh. This corresponds to a linear 
velocity of 1.7 fps and a mass velocity of 2,450 lb 
per hr per sq ft, based on the free cross section of 
the tower (total area minus downcomer area). The 
highest liquid-vapor ratio used in the tests was 1/57, 
which is higher than the usual range of interest in 
oxygen separation, but probably even considerably 
higher ratios would not result in appreciable reduc¬ 
tion of the critical vapor load. 

The average tray efficiency was found to be con¬ 
sistently high over the entire range of liquid feed 
rates studied. From the lowest feed rate, 2,550 scfh, 
up to the flooding point, 5,700 scfh, the reboiler vapor 
analysis was constant at 97% oxygen at total reflux. 
The number of theoretical plates required for this 
separation was estimated at 3/7, and thus the aver¬ 
age tray efficiency, defined as the ratio of theoretical 
plates to actual plates, was constant at 93% for the 
four-tray tower. 


Rocking Conditions 

Steady-state conditions were achieved at two mo¬ 
tions, a pitch of 3% degrees each side of vertical at 
a frequency of 5 cycles per minute without roll, and a 
roll of 15 degrees at 2 cycles without pitch. The 
tray efficiency and capacity were unaffected by these 
types of motion. Further runs were made with a 
Z l / 2 -degree, 4-cycle pitch both alone and combined 
with the 15-degree, 2-cycle roll, and although steady- 
state conditions were never reached, the results in 
general showed that the tower performed about the 
same while rocking as when stationary and verti¬ 
cal. 18 - 19 

It was concluded that a type J tray tower would 
function as well on shipboard as in stationary service, 
and this in addition to the high-tray efficiency and 
reasonably low-tray spacing made the design appear 
quite attractive for the M-5 low-pressure liquid oxy¬ 
gen pilot plant for submarine propulsion application. 
Accordingly a large type J tray tower was con¬ 
structed and installed in the M-5 unit. This tower 
consisted of 16 trays each having four adjacent com¬ 
partments, with the compartments about 25 per cent 
larger than the single compartment used in the small 
test tower. Vapors from the four sections can inter¬ 
mix to some extent between trays, but the four 
liquid streams remain separated. 

The column functioned satisfactorily in the unit, 
although the average tray efficiency was only about 
75 per cent, which is considerably lower than the 
93 per cent value obtained in the test tower. The 
reduction was attributed mainly to unequal liquid 
distribution to the four tower sections. 20 

8 7 5 Other Small-Column Tests 

Tests were made on the column of the Keyes unit 
to evaluate shoe eyelets and the use of a spiral in¬ 
serted in the column before filling with the eyelets. 5 
The screen was supposed to increase the efficiency by 
providing a longer path for the liquid, but the runs 
were in the flooding region, and only one point is 
given for the tower without the spiral. The plain 
tower probably has more capacity than the tower with 
the spiral. 1 

8 7 6 Rotary Rectifiers 

In an effort to develop a small-size, high-efficiency, 
high-capacity column for the Collins unit, experi¬ 
ments were made on power-driven rectifiers. 5 - 25 




TOWERS DESIGNED FOR NDRC UNITS 


177 


These rectifiers consisted essentially of a plain or 
studded cylinder rotating within a cylindrical shell, 
with fractionation taking place in the annular space 
between rotor and case. 

The data on benzene-ethylene dichloride fraction¬ 
ation give an indication of the performance of these 
various rectifiers and permit the following conclu¬ 
sions. 1 

1. The behavior of the rectifiers is unaltered when 
made to operate in steeply inclined positions, 0 to 37 
degrees, except at very low rpm. 

2. For small throughputs there exists an optimum 
rpm above which the rectifying action is decreased, 
probably due to hack-mixing of the vapor. For high 
throughputs, the vertical vapor velocity in the range 
of rpm studied is great enough to prevent any appre¬ 
ciable back-mixing. Probably the effect would have 
been found at sufficiently high speeds. 


6. At constant rpm there exists an optimum 
throughput above which the efficiency or number of 
transfer units, NTU, is decreased. This is, in gen¬ 
eral, noticeable between 2,000 and 3,000 rpm and 
12 to 13 fps superficial velocity. It should be noted 
that the superficial velocity is based on the total 
cross-sectional area of the case. In the 6-in. OD 
column the annular area is only 23}4% of the case 
cross-sectional area. 

A rotary shoe-eyelet packed column was used in 
the final models of the Keyes units but performance 
data are not yet available. The Badger Company 
units built for the Navy likewise had rotating col¬ 
umns installed in some cases but final performance 
data are not available. 

Many variations of plate columns were also ex¬ 
perimented with and complete details can be found 
on their performance in the references. 1 


Table 3 


Unit* 

Feed rate scfh 

Oxygen product 

Liquid 

Vapor 

Rate scfh 

Purity 
per cent 0 2 

M-l 

6,000 

0 

1,000 

99.5 

M-2R 

8,000 

4,000 

1,000 

99.5 

M-3 

2,800 

1,950 

380 

99.0 

M-4 Giauque 

5,700 

0 

57 lb/hr 

99.5 

M-5 

31,200 

19,000 

384 lb/hr 

99.5+ 

M-6 

36,500 

20,300 

453 lb/hr 

95.5+ 

M-7 

8,000 

4,000 

1,150 

99.5 




1,300 

99.0 

M-8 

7,000 

5,000 

1,000 

99.0-99.3 

M-10 Air Reduction 

3,000 

0 

400 

99.2-99.4 

M-ll Keyes 

4,000 

0 

36 lb/hr 

99.1-99.4 

M-12 Little-Latham 

4,000 

0 

14 lb/hr 

99.5 

M-13 Collins 

1,500 

0 

150 

99.5 

M -27 

8,000 

4,000 

Same as M-7 


M-31 Le Rouget 

6,000 

0 

54 lb/hr 

99.0 

E. B. Badger unit 

4,500 

0 

580 

99.5 

Independent Engrg. Co. unitf 

6,250 

0 

600-800 

99.5 

M. W. Kellogg-Ft. Belvoir unit 

6,250 

0 

800 

99.5 


* See Chapters 3 and 4. t This is not an NDRC development. 


3. Doubling the clearance between the rotor and 
the case causes only a slight decrease in rectifying 
ability and power consumption of the rotor. 

4. The power supplied to the rotor increases rap¬ 
idly as the boil-up rate, or throughput, is increased. 

5. The HETP is greatly reduced by putting axial 
rows of pins in the case. These pins mesh with the 
blades of the rotor providing better contact and, 
therefore, increasing the rectifying action of the col¬ 
umn. The power requirement of the rotor is in¬ 
creased, but the decrease in HETP makes it possible 
to operate at lower rpm. 


8 8 PERFORMANCE OF TOWERS 
DESIGNED FOR NDRC 
UNITS 

Towers designed for various NDRC units have 
been tested under operating conditions. Table 3 lists 
the unit designation and the more pertinent operating 
or design figures. 

Results of operation of these towers are completely 
summarized in the M. W. Kellogg report. 1 Only a 
few of the most successful applications will be indi¬ 
cated here. 









Table 4. Liquid air fractionation performance of the M-7 mobile low-pressure oxygen unit. 


178 


LIQUID AIR FRACTIONATION 


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TOWERS DESIGNED FOR NDRC UNITS 


179 


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8.8.1 The Kellogg Tray Tower for the 
M -7 Unit 

The most successful large tower for low-pressure 
work was the one built for the M-7 unit and the Clark 
production models. This tower, Figure 39, had trays 
similar to Figure 40. It is difficult to divorce the 
column performance from that of the unit as a whole ; 
therefore the data are summarized in Table 4 for the 
unit as a whole. Figure 41 illustrates the character¬ 
istics of the column itself. 

The oxygen purity is shown as a function of the 
production rate and the percentage yield. These data 
show that the unit with this tower easily meets the 
design specifications of 1,000 scfh of 99.5% oxygen 
from a minimum air feed of 11,300 scfh. The shape 
of the production curve shows nothing unusual as it 
is the same type as that obtained with the test tower. 

From time to time it has been suggested that the 
Stedman tower rather than the tray tower should be 
used in the mobile units. Proponents of this idea 
point out that the starting time of a unit is a very 
important quality, and that 50% to 60% of the M-7 
starting time is used in merely filling the trays with 
liquid. In the case of Stedman packing, the tower 
is ready for some sort of fractionation as soon as 
liquid is introduced and reboiling has begun. 

Although it is true that a Stedman column is ready 
for operation with a very small amount of liquid, the 
efficiency of the tower under these conditions is poor. 

The starting time of a packed column unit is less 
than that of a tray tower by the time required to 
fill the trays with liquid, but the packing does not 
reach its peak efficiency until it too has some liquid 
holdup. The quantity of the holdup and, therefore, 
the time required to reach peak efficiency is depend¬ 
ent upon the liquid and vapor loads of the tower. On 
the other hand, a tray tower will produce nothing 
until the trays are full, but once this point is reached 
the oxygen recovery in a given height is greater than 
that for the large packed towers tested. In addition, 
the performance of the tray tower is much more de¬ 
pendable and reproducible. 

8 8 2 Fort Belvoir Unit 

The title given to this unit is somewhat misleading 
as the connection with Fort Belvoir is not obvious. 
The Engineer Board had expressed some dissatisfac¬ 
tion with the performance for their specific purposes 
of the early Independent Engineering units. After 
the successful tests on the Kellogg 29-tray tower 












180 


LIQUID AIR FRACTIONATION 


PRESS GA CONN 



and the unsuccessful test on the Independent Engi¬ 
neering Company tower at Pennsylvania State Col¬ 
lege, it was suggested that a Kellogg tower he in¬ 
stalled by NDRC in an Independent unit at Fort 
Belvoir, Virginia. Later, through the co-operation of 
the Independent Engineering Company, the NDRC 


tower was installed and tested at the Independent 
plant at O’Fallon, Illinois. The name, “Fort Belvoir 
Unit,” has remained although the tower has not been 
at Fort Belvoir. 

This column was similar to that shown in Figure 
39 and it operated successfully. Largely as a result 















































































































TOWERS DESIGNED FOR NDRC UNITS 


181 


of these tests the column arrangement of the units 
built for the Engineer Corps and the Army Air 
Forces by the Independent Engineering Company 
was modified and simplified and the production im¬ 
proved. 



Figure 40. Type C tray similar to those used in the M-7 
tower. 

8 8 3 Giauque Unit (M- 4 ) 

This mobile unit was designed to produce 1,000 
scfh of oxygen as liquid. 7 The Linde cycle with, a 
cascade refrigeration system using butane and ethane 
was originally contemplated. However, Freon-12 
was later substituted as a single refrigerant. The 
tower system (Figure 1) has the provision for nitro- 



Figure41. Performance of the M-7 portable oxygen 
unit. 


gen recirculation which raises the recovery of oxy¬ 
gen from the high-pressure air feed. Because of the 
difficulty in obtaining an oil-free nitrogen compres¬ 
sor, the recirculation system has not yet been used 
and the unit has been operated only with the ordinary 
single-feed fractionating system. 

The tower is 12-in. in diameter and has thirty 
trays on a 2-in. spacing. Each tray has 85 bubble 
caps, triangularly spaced. In the development of the 
tower a test apparatus was used in which the tray 
action with air and liquid air could be observed visu¬ 
ally. 

The production of the unit is: 

Air feed 5,700 scfh 

Oxygen production 60 lb per hr (700 scfh) of liquid 

Oxygen purity 99.67% 


8 8 4 Air Reduction Company Mobile Unit 

This is a high-pressure, Freon-forecooled, single¬ 
tower unit. The reboiler is of the coiled type so that 
the reflux is subcooled to approximately the tempera¬ 
ture of boiling oxygen. A description of the tower 
follows. 


6 in. Bubble caps: 
ft 


Diameter 

Overall height 8 ft Number per tray 

Number of trays 24 Spacing 

Tray spacing 3% in. Diameter 

Downflow pipe Height 

y 2 in. diameter (1 per tray) Riser diameter 


12 

li/s, in. centers 
1 in. 

1 in. 

Vt. in. 


The following tower performance has been ob¬ 
tained. 


No. theo- Overall 


Air feed 

Oxygen 

retical 

tray effi¬ 

HETP 

scfh 

scfh 

%0 2 

trays 

ciency 

inches 

3,000 

390 

99.2-99.4 




2,950 

370 

99.54 

22 

92 

3.4 

2,400 

300 

99.3 

19 

79 

4 

2,400 

240 

99.7 

15.5 

65 

4.8 


Column pressures 11 psi 


These figures, while showing the performance of 
the unit, do not represent data for tray efficiency cal¬ 
culations. However, considering the highest effi¬ 
ciency given, the HETP is 35% greater than that 
obtainable with a Kellogg tray at a 2-in. spacing. 

8 8 5 E. B. Badger Unit 

The E. B. Badger Company built high-pressure 
units (see Chapter 4) for the United States Navy, 
using a rotating column packed with Y\-w\. by >4-in. 
McMahon wire gauze saddles. The performance of 





















182 


LIQUID AIR FRACTIONATION 


the unit is described in part by the Badger Company 
as follows. 

We have tabulated a series of 26 runs made between De¬ 
cember 23 and February 19 and obtained extremely un¬ 
satisfactory and inconsistent results. Probably the most im¬ 
portant results are the following: The highest purity at the 
highest yields were obtained with rather low throughputs. 
This would indicate that the efficiency of the packing cer¬ 
tainly did not increase as the throughput increased. The 
results with the column not rotating are scattered through 
the results with the column rotating, indicating that there 
is not enough difference between the rotating and non-rotating 
vertical column to show up in such inconsistent data. 

The object of the runs on this rotating column was never 
primarily to obtain data on the column, but to develop a 
practical unit that would meet the requirements of the Navy. 
For this reason, we do not believe that any good purpose 
would be served in submitting detailed data on the runs. The 
use of such data by itself could only cause trouble. 

If we now had to give a guess as to the most likely figures 
to use for the performance of this 4.7 in. diameter column 
with 36 in. packing, rotating or non-rotating, and with a head 
in which the unliquefied material was separated above the 
packing, we would say that it lay close to 99.5% purity and 
14.3% by weight yield on the net air charged at capacities 
running between 63 and 76 cfm of charge air. The results 
appear to be slightly better when the column was inclined up 
to 10 degrees and rotated. 


saddles, the third size (^4-in.) much better than Berl 
saddles, and each weighs less than one-third as much. 
Their heat capacity is about one-tenth as great. The 
maximum throughput of the screen saddles is more 
than twice as great as the ceramic ones. 

The performance data are summarized in Figure 
42 for the column shown in Figure 43. 


8 8 7 M-5 Low-Pressure Unit 

The first column designed for this unit was of 
Stedman packing and arranged as shown in Fig¬ 
ure 44. 

Results on operation of the tower were disap¬ 
pointing 16 ’ 17 and the tower was replaced by one made 
of J trays (see section 8.7.4). The J tray tower lay¬ 
out is shown in Figure 12. The design rates for the 
tower are 


Liquid feed 
Vapor feed 
Oxygen product 
Oxygen purity 


2,389 lb per hr (31,200 scfh) 
1,453 lb per hr (19,000 scfh) 
384 lb per hr (4,500 scfh) 
95.5% or better 


M-6 Medium-Pressure Unit 


The data from one performance are tabulated 
below. 


This is a medium-pressure unit with high-level and 
low-level expansion engines. Consequently, it was 


Table 5 


Feed rate 
scfh 

scfh 

Oxygen Product 

Purity 

Per cent O, 

Yield scf 
per 100 scf 
liquid feed 

• 

Number of 
theoretical 
plates 

Packed 

height 

inches 

HETP, 

inches 


3,750 

520 

98.6 

13.9 


47 


Tower ro- 

3,720 

450 

99.85 

12.1 

26 

36 

1.38 

tating at 

4,400 

575 

97.45 

13.1 

11 

36 

3.3 

18 rpm 

3,800 

490 

99.5 

12.9 

27 

36 

1.33 

Estimated 

4,500 

580 

99.5 

12.7 

27 

36 

1.33 

best tower 
performance 

8.8.6 

Collins-McMahon Unit 


possible to use 

the vapor 

feed type of 

tower. The 


This is a lightweight, compact unit originally in¬ 
tended for operation in aircraft. 25 Air compressed to 
150 psi, after heat exchange and expansion through 
an engine, is condensed in the reboiler and fed to a 
single tower as liquid feed. 


tower, shown on Figure 45, was originally designed 
to be packed with either ^4-in. Berl saddles or rings 
hut trays were finally used. See Figure 37. 

The tower description and design loads are as 
follows. 


Aside from the unit itself two contributions have 


been made to the fractionation program. These are 
the introduction of the differential reboiler and the 
wire gauze saddles. 

Wire gauze saddles made from 100-mesh wire 
cloth have been used. The second size ( 46 -in. square 
of cloth before forming) performs as well as Berl 


Tower 

Total trays 
Above vapor feed 
Below vapor feed 
Liquid feed 
Vapor feed 
Oxygen produced 
Oxygen purity 


27 

2 to 5 15 /iq in. spacing 
25 to 3p2 in. spacing 
2,791 lb per hr (36,500 scfh) 
1,567 lb per hr (20,300 scfh) 
453 lb per hr ( 5,350 scfh) 
95.5 per cent or better 









HE TP, INCHES PRODUCT PURITY, PER CENT OXYGEN 


AIR-WATER TESTING OF TRAYS 


183 




SCF OF OXYGEN PER IOO SCF OF AIR FEED 


Figure 42. Performance of a tower packed with wire 
gauze saddles. 



differential type 


Figure 43. Collins unit tower. 


8 9 AIR-WATER TESTING OF TRAYS 

The technique of air-water testing has proved in¬ 
valuable in the development of trays for efficient 
oxygen production. 1 ’ 8 The procedure is merely that 
of duplicating the normal liquid and vapor flows in 
a tower, measuring rates of flow and entrainment, 
and making visual observation of the effects. The 
materials are used at room temperature and pressure 
to allow easy operation and almost complete visual 
observation of the tray behavior. 

One essential difference between packing and trays 
as a fractionation device is the extreme complexity 
of the design of tray towers as compared to packed 
towers. In the case of trays the efficiency and ca¬ 
pacity are sometimes such obscure functions of the 
mechanical factors that tray design is still an art 
rather than a science. An added complication is that 
trays do not necessarily conform to the theory of 
models. A design which is satisfactory in one size 
of tower must often be entirely altered if the diameter 
of the tower is changed. 

Some of the factors which must be considered in 
designing a tray are: tray spacing; tray area; riser 
area; downflow area; slot area and dimensions; num¬ 
ber, type, and arrangement of bubble caps; slot sub¬ 
mergence ; liquid gradient; and entrainment. 

If tray towers are to compete with packed towers 
it is necessary to use a tray spacing of about 2 in. 
At such a low spacing the elements of design become 
very important in the performance of a tray. 

The design of trays with this very low spacing 
appears to be a subject which has not received much 
attention by the oxygen industry. For instance, the 
Air Reduction Company stated that the efficiency of 
height utilization is the same for 3-in. as for 4-in. 
tray spacing; over 4 in. the HETP increases simply 
because of the extra spacing. Between 4 in. and 3 in. 
the entrainment offsets the decreased spacing, where¬ 
as below 3 in. the entrainment is high enough to coun¬ 
ter the reduced spacing and the result is flooding of 
the trays and a greatly increased HETP. Another 
example is the Independent Engineering Company 
tray which had a low capacity. These two instances 
suggested that in designing a low-spacing, high-ca¬ 
pacity tray the principal problem is the removal of 
inter-tray entrainment. To do this requires the use 
of entrainment separators and a tray layout which 
minimizes splashing. 

In the process of development, a few trays were 
fabricated according to a tentative design and the air- 





































































184 


LIQUID AIR FRACTIONATION 












































































































































AIR-WATER TESTING OF TRAYS 


185 

















































































































Table 6. Tray characteristics and areas 


186 


LIQUID AIR FRACTIONATION 


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* “Slot Area” consists of holes in perforated plate. t Area in tubes. (Top downflow area = 0.208 sq ft.) 

f Minimum areas permitted by tolerances. § Area at outlet of cap under perforated plate. 

II Tower area for Airco trays assumed to equal area of 4 in. x 1 *Vi6 in. compartments, that is tower area, sq ft = (No. of compts.) x (4 x 1 1 Vie)/144. 
























DIFFERENTIAL REBOILER 


187 


water tests made with these. With the aid of some 
sheet celluloid and metal and some ordinary adhesive 
tape, a great many trial-and-error tests were made 
before the final design was established. The investi¬ 
gation was concerned particularly with entrainment 
removal, equal distribution of liquid in the bubbling 
channels, and the uniform activity of all slots. In 
other words, although the tray efficiency cannot be 
obtained with the air-water tests, all the factors 
which affect the efficiency can be considered. 

In addition to the qualitative observation of the 
behavior, the following variables were measured 
quantitatively: liquid level in downflow, height of 
liquid over the downflow weir, liquid gradient across 
the tray, froth height, pressure drop, liquid and vapor 
quantities, and entrainment. 

At least two trays are required for air-water tests. 
If only one is used, the entrainment cannot be meas¬ 
ured, and in addition a tray exerts a considerable 
influence upon the pattern of vapor flowing from the 
tray beneath. 

In order to apply the air-water capacity data to 
other systems, the liquid rate in gallons per hour at 
flooding is plotted against the flooding gas velocity. 
The superficial vapor velocity is taken as Z. When 
used in this manner, the air-water capacity data agree 
almost exactly with the liquid air data. 

All tray types except the A and B trays were 
developed by the air-water procedure. The Type B 
trays were not used in any units but became the Type 
C after testing. Type A trays, used in the M-l unit, 
were tested only in the completed tower. For a com¬ 
plete description of the technique of air-water testing 
see reference. 1 

In addition to the Types C, D, E, F, J, and K 
trays and the West tray, an exhaustive study was 
made with the Independent Engineering Company 
tray to discover the reason for its poor test perform¬ 
ance. The characteristics of all these trays are given 
in Table 6. 

8.10 DIFFERENTIAL REBOILER 

The idea of utilizing progressive or differential 
vaporization of the boiling liquid in a tower was first 
utilized in the Collins-McMahon unit. 

A schematic representation on the McCabe-1 hiele 
diagram of differential distillation and the perform¬ 
ance of a perfect differential process are shown by 
Figure 46. 

The enrichment obtained by a perfect differential 


vaporization process in air fractionation is a function 
of the tower yield and the composition of the liquid 
entering the vaporizer. 



PER CENT OXYGEN IN LIQUID 



PER CENT OXYGEN IN PRODUCT 

Figure 46. Analysis of differential vaporizer perform¬ 
ance. 

There are two general types of progressive vapor¬ 
izers. 1 The first is the straight simple or differential 
distillation in which the vapor is removed as it is 
formed. The Collins-McMahon reboiler is an ex¬ 
ample of this type. A perfect vaporizer is one with an 
infinite length of heat transfer surface. 

The second is one in which the vapor passes back 
over the liquid path. This type should give better re¬ 
sults than the first kind, because at any point the 
vapors returning are leaner in the contaminant than 
the mixture which would be in equilibrium with the 





































188 


LIQUID AIR FRACTIONATION 


liquid. This means that there will be some oxygen 
concentration in the liquid through mass transfer be¬ 
tween the phases, in addition to the enrichment re¬ 
sulting from the progressive vaporization. 

The coiled type of reboiler used in the Collins- 
McMahon unit requires more cubic space per unit of 
reboiler surface than the tubular bundle type, al¬ 
though the coil seems vastly superior in differential 
vaporization. For this reason and because construc¬ 
tion was under way when the idea was proposed, the 
coiled type reboiler was not used in the units designed 
by the M. W. Kellogg Company. 

Since use of a differential reboiler offers the op¬ 
portunity of improving the product purity and of low¬ 
ering the height of a tower, the subject is worth 
further study. The data available on performance of 
progressive vaporizers are open to criticism, the M-3 
because of its uncertainty, and the Collins-McMahon 
data because of its incompleteness. Future study 
should involve the analysis of all streams entering and 
leaving the boiler. 

811 SUMMARY 

It is believed that the data obtained in this program 
should be valuable in the design and construction of 
any liquid air fractionation system by enabling—(1) 
the estimation of the theoretical trays required for 
any system, (2) the design of any packed tower 
through accurate knowledge of the efficiency and ca¬ 
pacity of many packing materials, (3) the design of 
a tray tower using the trays developed by the Kellogg 
Company and the performance data on these trays, 
and (4) the use of expansion engine exhaust air to 
increase the oxygen recovery of low-pressure plants. 
The data which have been obtained and are essential 
to the actual design of towers are presented in the fol¬ 
lowing section. 

8 12 CALCULATION OF THEORETICAL 
TRAY REQUIREMENTS 

A chart (Figure 4) has been presented, which 
gives the number of theoretical plates required to 
make any required oxygen recovery and purity in 
simple single columns. In the design of a different 
type of column, the necessary number of theoretical 
trays may be obtained by rigorous tray-to-tray meth¬ 
ods of heat and material balances, and equilibrium 
calculations. The atmospheric pressure vapor-liquid 
equilibrium constants to be used are given in Table 


1. Further experimental equilibrium data at elevated 
pressure will extend the scope of tray-to-tray calcula¬ 
tions. 

Given the required number of theoretical trays and 
the quantity of liquid air to be treated, it is possible 
to select a packing or a tray and to set the required 
size of the tower. Conversely, if the tower size is 
fixed by other considerations it is possible to de¬ 
termine the oxygen recovery and purity, and the 
amount of air which must be handled. 

The choice between trays and packing will depend 
upon a number of factors which may vary from unit 
to unit. For instance, if a short starting time is re¬ 
quired, then a medium having a low refrigeration 
load is indicated. This might be a metallic packing, 
such as shoe eyelets, with low liquid holdup and low 
heat capacity. On the other hand, if stability of oper¬ 
ation were the prime consideration then a tray tower 
would be the proper choice. 

8 13 PACKING MATERIALS 

The efficiency and capacity of all the packings 
tested in the 2-in. column are given in Table 2 and 
Figures 15 and 16. Of all those tested, the shoe eye¬ 
lets, glass rings, Lessing rings and the Stedman pack¬ 
ing seem to be the best. The gauze saddles developed 
by Collins-McMahon apparently perform favorably, 
but the data available are meager. 

The HETP values should he used with caution 
when applied to large diameter towers. It may be 
that the decrease in efficiency is entirely the result of 
poor liquid distribution. This may be overcome by 
proper initial distribution, followed by successive re¬ 
distributions. However, it is impossible to predict 
the performance of such devices. 

Figure 47 shows the HETP for various trays and 
packed towers plotted as a function of oxygen re¬ 
covery. The fact that the efficiency of the short 
tray towers is independent of oxygen recovery indi¬ 
cates that the variation in the HETP of the taller 
packed towers may be fictitious. An explanation of 
this is that the oxygen purity was low enough in the 
short tray towers so that the effect of analytical error 
was minimized. Therefore, it might not be too un¬ 
reasonable a procedure to use the lower values of 
HETP in tower design. However, a safer procedure 
would he to use the actual performance data, such 
as shown in Figure 48. 

To determine the diameter of a tower the capacity 
of the various packings listed in Table 2 should he 



TRAYS 


189 



Figure 47. Relation between yield and efficiency for various columns. 


used. In correcting the flooding point to pressures 
other than atmospheric, the flooding vapor load may 
be taken as approximately proportional to the square 
root of the absolute pressure. A correlation, avail¬ 
able in the literature, 24 relating the flooding loads in 
packing to the properties of the liquid, vapor, and 
packing, satisfactorily fits most reported data for 
other systems. However, when applied to liquid air, 
this correlation predicts flooding velocities which 
vary from 30% to 70% of the observed values. 
Therefore, flooding points for untested packing must 
be obtained experimentally. 


814 TRAYS 

Nine different trays have been developed for 
various purposes by the application of air-water test¬ 
ing. This relatively simple technique has proved to 
be most reliable in predicting the capacity of trays 
and reasonably accurate in estimating entrainment. 
The liquid and vapor capacities for all trays tested 
are given on Figure 49. Owing to the nature of 
trays, these data should be used only as a guide for 
any other diameter tray or type of design. Efficiencies 
of all the trays are in the range of 75% to 80%. 











































































190 


LIQUID AIR FRACTIONATION 



Figure 48. Large column performances. 


8 15 USE OF VAPOR FEED 

In some low-pressure units using a Claude type 
refrigeration cycle, the air exhausted from the ex¬ 
pansion engine at too low a pressure to be condensed, 
may be used as vapor feed to a single liquid feed 
tower. The successful use of this scheme in the 
Kellogg test tray tower is shown by Figure 33. This 
chart is fairly indicative of the increase in oxygen 
recovery which may be expected from any reasonably 
well designed tower using this system. Figure 50 


shows the oxygen recovery based upon a constant 
total amount of air for three cases: (1) all the air is 
fed as liquid reflux to the tower, (2) a fraction of 
the air is expanded and sent to the tower as vapor 
feed, and (3) the same fraction of the air is ex¬ 
panded but is not used in the tower system. 

This plot shows that with a single tower, the 
oxygen recovery may be greatly increased by use 
of the vapor feed, and that for a fixed air supply it 
is advantageous to keep the quantity of air expanded 
as low as possible. 



































USE OF VAPOR FEED 


191 



Z = (TOWER VAPOR VELOCITY F P S X IOO ) / (0.227 ) 


Figure 49. Capacities of tray columns. 


100 
99.8 
99.6 
z 99.4 

UJ 

o 

X 99.2 
o 

55 99 0 
> 

E 98-8 


- r 1 -r 



. NOTE: ^ 

OXYGEN YIELD IS GIVEN FOR A 
CONSTANT AMOUNT OF AIR 
COMPRESSED. PURITIES AND YIELDS 
ARE BASED ON M WK 29 

TRAY TOWER TESTS AT THE PENN 






\ 


A 


B\ 

C 


STATE C 

OLLEGE 
































RATIO 

VAPOR FEED 
LIQUID FEED 
0.6 
0.6 
0 


TOWER SYSTEM 

SINGLE LIQUID FEED,VAPOR NOT USED 

VAPOR FEED USED IN TOWER 

ALL AIR COMPRESSED IS FED AS LIQUID 


SCF OXYGEN YIELD PER 100 SCF AIR COMPRESSED 


Figure 50. Effect of feed on oxygen purity and yield. 









































































Chapter 9 


AIR PURIFICATION 

By /. H. Rushton 


91 INTRODUCTION 

T hree constituents of ordinary atmospheric air 
must be removed for air liquefaction processes 
or for the conditioning of submarine air. These sub¬ 
stances are water, carbon dioxide, and hydrocarbons. 
Liquid water and hydrocarbons are removed by fil¬ 
tration or settling but gaseous water and hydrocar¬ 
bons must be removed by other means. 

The following sections of this chapter will deal 
with the various methods of removing these sub¬ 
stances, and will show where such methods are 
applicable. 


9 2 DRYING OF AIR BY SOLID 
ADSORBENTS 

In any low-temperature process for the separation 
of air components, removal of water from the process 
air is a necessity. This removal is accomplished in 
some processes by freezing out the water in a heat 
exchanger and then deriming (see Chapter 3) as in 
the case of a switch exchanger, or re-evaporating as 
in the case of the reversing exchanger or regener¬ 
ator. In addition to these mechanical methods, water 
removal may be effected by the use of solid adsorb¬ 
ents. Such a method has distinct advantages in some 
cases, especially where high operating pressures are 
employed. A particular situation where solid drying 
agents find application is in the removal of water 
from pure oxygen, which has been compressed in 
machines lubricated with water or an aqueous soap 
solution. In anticipation of a demand for data to 
design drying systems for the applications indicated 
above, an investigation of the performance character¬ 
istics of several desiccants was undertaken. 

In the course of this investigation the effects of 
the following variables on dryer performance when 
using air were evaluated 1 : (1) air pressure, (2) air 
temperature, (3) air humidity, (4) air velocity, (5) 
duration of drying period, (6) desiccant used, (7) 
particle size of desiccant, and (8) desiccant bed length 


to diameter ratio. Drying performance was judged 
by the capacity of the bed and the exit air humidity. 

Two sets of apparatus were constructed. One was 
for high-pressure operation and the other for low 
pressure. The high-pressure dryer proper was a tube 
with an inside diameter of 1 in. and of such length 
that it could be filled with from 10 to 4 in. of 
desiccant. Compressed air was fed to this dryer after 
first being passed through two water-filled satur¬ 
ators and a trap for entrainment removal. All units 
of this system were immersed in a constant-tempera¬ 
ture bath. The discharge air from the dryer was 
throttled to atmospheric pressure through a dew 
point meter and a gas meter. No provision was made 
for the regeneration of the desiccant in situ. 

The low-pressure dryer consisted essentially of a 
42-in. section of 8-in. standard pipe set in a vertical 
position. Two inches from the bottom a screen, rein¬ 
forced with a perforated plate, was installed to sup¬ 
port the desiccant. Cooling coils spaced 6 in. apart 
were installed in the dryer, and thermocouples for 
the measurement of gas and bed temperatures were 
provided. Compressed air, to which a controlled 
amount of steam could be added, was fed to a 
suitable cooler and trap, and then to the dryer. Air 
from the dryer was metered by an orifice and dis¬ 
charged to the room. To regenerate the bed, flue 
gases formed by the combustion of city gas under 
a conical hood were drawn down through the dryer 
by a compressor. The compressor was protected by 
an ample cooler and filter, which were placed ahead 
of it, and the discharged gases were cooled, filtered, 
and metered to the room. After reactivation, the bed 
was cooled by passing water through the pancake 
coils. 

In carrying out a test, saturated air at a fixed 
temperature and pressure was fed to the dryer, and 
the exit dew point was measured as a function of 
time. Dew points were measured with a General 
Electric dew-point meter and also with a homemade 
instrument patterned after the GE instrument. 

The data obtained, and discussions of the experi¬ 
mental results are given in detail in the refer¬ 
ences. 4 ’ 5 - 6 - 7 ’ 9 - 10 - 11 - 12 - 13 


192 


DRYING OF AIR BY SOLID ADSORBENTS 


193 


9 21 High-Pressure Air 

The experiments with the high-pressure dryer 
covered a pressure range of 100 to 2,000 psi and a 
temperature range of 80 to 150 F. In all cases 
saturated air was used and the flow rates extended 
from 1,000 to 4,200 standard cubic feet of air per 
foot of desiccant. Drying agents of the following 
varieties and sizes were tested : 4- to 8-mesh alumina, 
8- to 16-mesh Florite, 8- to 14-mesh silica gel, and 
8- to 14-mesh potassium hydroxide. To discover 
the effect of bed geometry, bed length to diameter 
ratios of 10/1 and 4/1 were used. In preparation 
for the tests, the desiccants were regenerated with 
flue gases at 450 to 510 F for 4 hrs, except in the 
case of silica gel, where a regeneration temperature 
of 370 to 470 F was used. 

The experimental results indicated bed capacities 
ranging from 4.9 to 13.1% and minimum dew 
points ranging from —30 to —109 F. It was found 
in general that the dew point of the exit air decreased 
with time to a minimum, and then remained fairly 
constant until the break point. This “induction 
period” in which the desiccant was not working at 
top efficiency w r as found in all cases except with 
potassium hydroxide. 

In the course of the drying tests the following ob¬ 
servations were made. 

1. The break-point capacity was reduced as the 
temperature of drying was increased. 

2. The same was true of the —70 F dew point 
capacity (per cent of water absorbed to bed weight 
when exit air humidity has reached —70 F). 

3. The minimum dew point was increased (that 
is, the air is less dry) as the drying temperature was 
increased. 

4. The break-point capacity was increased as 
pressure was increased. 

5. The same was true of the —70 F dew point 
capacity. 

6. The minimum dew point was lowered as pres¬ 
sure was increased. 

7. Both capacities were decreased slightly as space 
velocity was increased. 

8. Minimum dew point was unaffected by space 
velocity. 

9. At 500 psia, space velocity of 6.000, and at all 
temperatures measured, the break-point capacity of 
silica gel was about 2 l / 2 times that of alumina. At 
85 F and the above pressure and flow conditions, 
silica gel exhibited about four times the capacity of 
Florite, and at 150 F about three times. 


10. The same general observations were true for 
the —70 F dew point capacity. 

11. At the same conditions as in (9) and at all 
temperatures, Florite exhibited an exit dew point 
about 5F above (less dry) silica gel and about 8F 
above alumina. The alumina dew points varied from 
—100 to —78 F at bed temperature of 85 and 150 F 
respectively. 

12. At the same pressure and flow conditions as 
in (9) and at 85 F, the capacity and exit dew point 
of potassium hydroxide was quite comparable with 
alumina. At 150 F, however, the exit dew point was 
much higher (less dry) than alumina. The capacity 
was not determined at this condition. Potassium 
hydroxide tends to channel the flow, particularly 
after an interruption of flow, and very poor per¬ 
formance results. This is probably caused by the 
formation of aqueous potash on the solid surfaces 
which can cement the particles and fill the crevices. 

It was concluded that alumina was the best 
desiccant, particularly at high air-space velocities. 
Although at low velocities, silica gel was found to be 
superior, with respect to capacity at least, high-space 
velocities are desirable for practical drying applica¬ 
tions, thus alumina is indicated. As a drying agent, 
potassium hydroxide was found to be unsatisfactory. 

9 2 2 Low-Pressure Air 

In the low-pressure apparatus the data were ex¬ 
tended to the pressure range of 100 psi down to 
atmospheric. The drying agent used was 4- to 8- 
mesh alumina packed in a bed having a length to 
diameter ratio of 4/25. Flow rates used varied from 
250 to 2,000 scfh per cu ft desiccant and the 
humidity of the inlet air ranged from 0.0005 to 
0.0014 lh water per lb dry air. Regeneration of the 
bed was accomplished by passing flue gas at 250 to 
500 F thru the bed for a period of from 1 to 5 hrs. 
Both adiabatic and isothermal operation were in¬ 
vestigated. 

The following observations were made in the 
course of the low-pressure experiments. 

1. Although the effect of drying temperature was 
not directly measured, it was observed. Thus, adi¬ 
abatic operation of the bed, which gave higher tem¬ 
peratures, showed considerable reduction in capacity. 

2. Adiabatic operation also caused an increase in 
dew point of about 6 to 7 F at low-flow rates, and 
about 15 F at high-flow rates. 

3. The capacity was increased at higher pressure 
operation. 




194 


AIR PURIFICATION 


4. The minimum clew point was lowered at higher 
pressure operation. 

5. The capacity was decreased as space velocity 
was increased, and this effect was particularly marked 
for adiabatic operation. 

6. The minimum dew point was relatively unaf¬ 
fected by space velocity in isothermal operation, but 
in adiabatic operation it was considerably increased at 
higher space velocities. 

7. The capacity of the dryer was increased as the 
temperature of regeneration was increased. A prac¬ 
tical maximum was 600 F where the gel begins to 
break down. 

8. The minimum dew point was decreased as the 
temperature of regeneration was increased. 

9. The capacity of the dryer was unaffected by the 
time of regeneration (between 1 and 7 hr), provided 
the regeneration occurred at 450 to 500 F. This was 
equally true of adiabatic or isothermal operation dur¬ 
ing the drying cycle. 

10. The capacity of the bed was markedly reduced 
as the entrance air humidity was reduced, a rather 
unexpected and very important observation. 

11. The exit dew point was markedly reduced as 
the entrance air humidity was reduced. 

9 2 3 Design Conditions 

The data obtained during this investigation of the 
drying of air by solid adsorbents are sufficient for 
the designing of dryers for most operating condi¬ 
tions. For high-pressure isothermal operation the 
following conditions may be cited as satisfactory, 
using alumina as a drying agent: pressure, 2,000 
psi; temperature, 85 F; air saturated at above pres¬ 
sure and temperature ; space velocity, 6,000 cu ft/hr 
cu ft; bed height, 4 in.; break-point capacity, 
10.88%; “—70 F dew point capacity,” 13.10%; 
and minimum dew point, —106 F. 

Satisfactory conditions for low pressure adiabatic 
operation using alumina as drying agent may be sum¬ 
marized as follows: pressure, atmospheric; inlet 
temperature, 70 to 80 F; bed height, 34 in.; space 
velocity, 980 cu ft/hr cu ft; break-point capacity, 
2.56%; minimum dew point, —86 F. 

For isothermal operation under the latter condi¬ 
tions the capacity would be 5.5% and the minimum 
dew point —90 F. 

For the development of the component parts of 
several oxygen plants the drying data obtained in the 
investigation outlined above proved useful in the 


design of dryers used in purifying air for process use 
both at high and low pressures. 11 

9 3 REMOVAL OF CARBON DIOXIDE 
FROM AIR BY CAUSTIC 
SOLUTIONS 

A simple method for removal of carbon dioxide 
from air consists of scrubbing the gas with a caustic 
solution in an apparatus which affords intimate 
contact between the two phases. Such a scheme has 
been widely used for gases containing relatively high 
concentrations of carbon dioxide, and data were 
available for the design of such systems. For carbon 
dioxide concentrations as low as that found in atmos¬ 
pheric air (330 ppm), however, data for use in de¬ 
sign were signally lacking. Since adequate purifi¬ 
cation procedures were essential to some oxygen 
processes and most useful in the preliminary develop¬ 
ment of the individual components embodied in any 
plant, an investigation was undertaken to evaluate 
the performance of a packed column in the removal 
of carbon dioxide from atmospheric air by means of 
a caustic solution. 14,15 As an extension to this pro¬ 
gram, the possibilities of another type of apparatus, 
the jet-type absorber, were given consideration, and 
preliminary data obtained. 

The investigation of packed towers was under¬ 
taken to obtain data for use in the design of com¬ 
mercial size units and two 12-in. diameter towers 
were built as experimental units. One of these towers 
was designed for use in studies involving operation 
on the suction side of a compressor while the other 
was designed for use at higher pressures (up to 300 
psia) on the discharge side of a compressor. The 
effect of the following variables was studied: air 
rate, liquor rate, operating pressure, packed height, 
and the comparative scrubbing efficiences of aqueous 
sodium and potassium hydroxide solutions. The 
effect of alkali concentration and the degree of con¬ 
version to carbonate was fairly well known from 
previous work with C0 2 -rich gas mixtures so that 
very little time was devoted to a study of these 
factors. 1 

The packed tower used in experiments at atmos¬ 
pheric pressure was designed on the basis of available 
data from the literature on the absorption of C0 2 - 
rich gas mixtures by alkalies. 2 The diameter was 12 
in. and the height 18 ft; j^-in. stoneware Raschig 
rings were used as packing. The construction of the 



REMOVAL OF CARBON DIOXIDE BY CAUSTIC SOLUTIONS 


195 


tower allowed a maximum packed height of 16 ft, 
although in some cases less packing was used. This 
tower is shown in F igure 1. The flow sheet for the 
low-pressure system is shown in Figure 2. 

From the data obtained at atmospheric pressure on 
the above tower, another tower was built to permit 


extension of the studies to elevated pressures. This 
tower was made 16 ft high to allow for liquor storage 
within the tower body and yet give a packed height 
of 10 ft (Figure 3). The packing used in this tower 
was 1-in. Berl saddles. The flow sheet for the high- 
pressure system is shown in Figure 4. 



4 BOLTS ON THIS 
JOINT TO BE 1" 
TOO LONG 4 


ELEVATION 



Figure 1. Low-pressure carbon dioxide scrubbing tower. 
















































































































































196 


AIR PURIFICATION 


In all the experimental runs, atmospheric air was 
used and the C0 2 concentration did not vary ap¬ 
preciably from the value of 0.0315% usually found 
in clean air. For the most part, a 2.5 N aqueous 
sodium hydroxide solution was used, previous work 
having indicated this to be the optimum alkali con¬ 
centration. Previous investigators had also deter¬ 
mined the effect of the degree of conversion of the 
alkali to the carbonate, and the solutions were always 
changed before this conversion became great enough 
to have an effect on the absorption coefficient. All 
the runs were made at the prevailing room temper¬ 
atures. 



In the course of the experiments, the effect of 
liquor rate on the absorption rate coefficient was 
determined at several conditions of packed height 
and gas rate. The results of these tests are shown 
graphically in Figures 5, 6, and 7. It was found that 
K g a, the overall absorption coefficient, based on the 
gas phase, varies as the 0.20 power of the liquor 
rate. Absolute values of the coefficient for various 
conditions can be obtained from the plots. 

From the data included in Figures 5, 6, and 7 the 
relationship between K g a, the overall coefficient, and 
G, the gas rate, was found to be of the form, log 
K g a = 0.35 log G -f- C for values of G up to 500 lb 
per hr per sq ft. Above this value the effect of gas 
rate becomes less marked, and for gas rate values of 
about 1,000 lb per (hr) (sq ft), K g a varies only as the 
0.15 power of the gas rate. The relationship between 
the overall absorption coefficient and the gas rate is 
illustrated in Figure 8. 

In the packed tower tests, three different packed 
heights were used. Performance of the tower as re¬ 


lated to packed height was somewhat erratic as shown 
in Figure 9. A partial explanation for the observed 
effects of packed height can be made by considering 
the conditions under which the data were obtained. 
For the shortest packing height the liquor distribu¬ 
tion may have been better and there might also have 
been some wetted wall effects in the empty tower 
section above the packing. In the case of the 10-ft 
packed height, the coefficients were lower than for 
the 16-ft height. Tests for the 10-ft height were made 
in the high-pressure tower where this was the maxi¬ 
mum packing height and end effects were eliminated. 
Also, for the high-pressure tower, the air processed 
was quite oily, and fouling of the packing may have 
occurred. Another factor to be considered in ex¬ 
plaining the apparent discrepancies in the results of 
the packing height studies is the fact that for the 
10-ft height 1-in. Berl saddles were used whereas 
Raschig rings were employed in the case of the other 
packing heights. 

Some tests were made to compare KOH and 
NaOH solutions for scrubbing efficiency. 3 The re¬ 
sults obtained are illustrated in Figure 10. Analysis 
shows that the values of the overall absorption co¬ 
efficient obtained, using a KOH solution, are from 
20 to 30% greater than those for a NaOH solution 
of equal normality. This difference is probably due 
in part to the different physical properties of KOH 
solution. For KOH solutions, K g a varies only as 
the 0.10 power of the liquor rate. If higher transfer 
coefficients were to be explained by increased reac¬ 
tion rate between KOH and C0 2 , the relative im¬ 
portance of the liquor rate would necessarily increase. 
Since this is not true, the superiority of KOH solu¬ 
tion over NaOH solution as a scrubbing agent is 
most probably due to differences in physical prop¬ 
erties as noted above. 

The effects of operating pressure on packed tower 
performance in the removal of C0 2 from atmos¬ 
pheric air were studied in the high-pressure tower 
previously described. The results, shown graphically 
in Figures 11 and 12, indicate that K g a decreases as 
the 0.5 power of the absolute pressure of tower 
operation. This effect was independent of gas and 
liquor rates. At the higher pressures, the variation 
of K g a with liquor rate becomes less and the effect of 
gas rate increases. 

In addition to the packed tower tests, the po¬ 
tentialities of a jet-type absorber were studied. The 
jet-type scrubbers investigated consisted, basically, 
of variable length-absorption tubes in series with in- 















































REMOVAL OF CARBON DIOXIDE BY CAUSTIC SOLUTIONS 


197 


nipples to be screwed into tapping to be made from either 

SIDE OF FLANGE 



Figure 3. High-pressure carbon dioxide scrubber. 


jectors. Actual mixing of the air and caustic was 
accomplished in the injector, and the mixture dis¬ 
charged into a horizontal tube, where absorption 
continued until the gas and liquid streams were 
finally separated. The operating characteristics of the 
jet-type scrubber were determined, and the effect 
of liquor rate, gas rate, length of absorption tube, 
diameter of absorption tube and injector type on 
absorption performance was studied. 14 

From the data obtained, it was evident that the 


liquid rate had very little effect on the absorption 
coefficient. Over the flow ranges investigated, the 
gas rate was found to have an appreciable effect on 
the absorption coefficient as shown in Figure 13. 
K,,a appears to be a linear function of the gas rate 
( K g a = 9.1 -j- 23.5 V, where V is the volume of the 
absorber in cubic feet). 

The information obtained in the investigation of 
packed tower performance outlined above makes 
possible the design of scrubbing systems for the re- 





































































































198 AIR PURIFICATION 



(g) INDICATES DRAIN LINE 
@ * PRESSURE MEASUREMENT 

(f) ' TEMPERATURE 

(R) - FLOW RATE 

(D " AIR SAMPLE 


Figure 4. Flow sheet for high-pressure scrubber. 



LIQUOR RATE* LB /HR SQ FT -NoOH 


Figure 5. Absorption of carbon dioxide by sodium hy¬ 
droxide in a packed height of 16 ft. 

moval of carbon dioxide from atmospheric air. Such 
a system was actually built for use in the testing and 
development of oxygen plants and their component 
parts. 16 ’ 24 The work done with the jet-type scrubber 
indicated the potentialities of such a device, especially 
where size considerations are important. 24 The lim¬ 
ited amount of work done with the jet-type scrubber 
prevents any conclusions as to optimum conditions 
and dimensions, but from the data now available an 
absorber of this type can be designed for a given job. 



Figure 6. Absorption of carbon dioxide by sodium hy¬ 
droxide in a packed height of 7.8 ft. 


9 4 REMOVAL OF CARBON DIOXIDE 
FROM HIGH-PRESSURE AIR 
BY MEANS OF SOLID 
ABSORBENTS 

The removal of carbon dioxide from the air feed 
to air liquefaction-rectification units can be accom¬ 
plished in numerous ways, such as by condensation 
to a solid at low temperature and removal by de¬ 
position or filtration, by washing the air with a solu¬ 
tion of caustic alkali, by passing the air over a bed of 
a solid absorbent such as potassium hydroxide or 
soda lime, or by adsorption on an active adsorbent 
such as carbon or alumina. 























































199 


REMOVAL OF CCh, BY MEANS OF SOLID ABSORBENTS 




Figure 10. Absorption of carbon dioxide by sodium- 
hydroxide and potassium-hydroxide solutions. 


LIQUOR RATE - LB PER (HR) ( SO FT ) - NaOH 

Figure 7. Absorption of carbon dioxide by sodium hy¬ 
droxide in a packed height of 10 ft. 



AIR FLOW RATE , 6, LB/ HR SQ FT 



LIQUOR RATE-LB PER(HR)(SQ FT) - NttOH 


Figure 11. Carbon dioxide absorption at elevated pres¬ 
sures. 


Figure 8. Relation between absorption coefficient and 
gas flow. 



LIQUOR RATE - LB PER HR SO FT - NaOH 



Figure 9. Effect of packed height on absorption coeffi¬ 
cient. 


Figure 12. Effect of liquor rate on absorption coefficient 
at elevated pressures. 



























200 


AIR PURIFICATION 



AIR RATE (CFM AT 76 F ( I ATM) 

Figure 13. Effect of gas rate on absorption coefficient. 

All these methods are employed in the various 
oxygen-producing units in use by the Armed Serv¬ 
ices or developed under the NDRC. Certain of them 
have been the subject of fundamental study. This 
section deals with the results of a study of the re¬ 
moval of carbon dioxide from high-pressure air by 
means of solid alkaline absorbents at ordinary temper¬ 
atures and by active absorbents at low temperature. 

A fundamental study of C0 2 absorbents embracing 
the widest possible range of temperatures, pressures, 
and C0 2 concentrations was beyond the limitations 
of time available. Since solid absorbents are used 
only in the high-pressure units in which Section 11.1 
was interested, attention was centered upon opera¬ 
tion at 3,000 psi; and since soda lime seemed prefer¬ 
able to caustic alkalies in most high-pressure units 
which now use chemical clean-up, attention was 
centered largely upon soda lime in this work. 

Existing information concerning the use of solid 
absorbents for C0 2 -air mixtures such as are repre¬ 
sented by a normal atmospheric air (C0 2 at 300 to 
400 ppm) was very meager. A rather restricted study 
of the use of soda lime for C0 2 removal from high- 
pressure air has been carried out by E. B. Badger 
and Sons Company but this work is of limited scope. 
Their results afford little basis for the design of ab¬ 
sorption equipment for units operating under other 
conditions of flow rate and C0 2 tolerance than those 
obtaining in the Air Reduction Company unit with 
which the work was done. The criteria of absorbent 
performance were simply the appearance of the 
liquid oxygen draw-off (milky or clear) and the 
plugging of the unit. No C0 2 analyses were car¬ 
ried out. 

In the present work, the performance of the ab¬ 
sorbent was followed by continual analysis of the air 


under treatment and, to some extent, by analysis of 
the exhausted absorbent. Some attention was paid 
to the water relationships with the object of determin¬ 
ing whether or not the absorbent possessed drying 
properties. The data have been evaluated in such a 
way as to allow reasonable extrapolations to be made. 

It was not possible in the time spent to study the 
effect of temperature and pressure variation (except 
for some data at about atmospheric pressure), but 
certain conclusions have been possible concerning the 
effect of variations in the concentration of C0 2 in 
the air. The chief variables studied were the effect 
of flow rate, linear velocity and, in the case of soda 
lime, mesh size. 

941 Carbon Dioxide Analytical Methods 

The requirements of an analytical method suitable 
for the purposes of this work follow. 

1. Accuracy and reliability for C0 2 concentra¬ 
tions of about 5 to 500 ppm (0.0005 to 0.05%). 

2. Rapidity, so that a continuously changing exit 
concentration can be followed. 

3. Freedom from the need for observing elaborate 
precautions to prevent contamination by ordinary lab¬ 
oratory air, or by C0 2 containing confining solutions 
(it must not be necessary, for example, to store 
samples over water or other liquids before analysis). 

These requirements immediately rule out such 
obvious methods as absorption by ascarite and 
weighing, titration of a large sample of air by stand¬ 
ard alkali (the classical Pettenkofer method), the 
Van Slyke manometric method and the standard gas 
analysis techniques including that using the sensitive 
Haldane apparatus. A specific example of the nu¬ 
merical magnitude of the quantities in a single 
analysis is: a 1-liter sample of air containing 50 ppm 
of C0 2 contains 0.05 ml or 0.1 mg of C0 2 , equiv¬ 
alent to 0.45 ml of 0.01V alkali. It is apparent that 
the measurement of small quantities such as these 
could not be done both accurately and rapidly, and 
that minute amounts of contaminants would introduce 
large errors. It is necessary, then, to increase the 
sensitivity of the method, or to find a way to collect 
and analyze a very large sample in such a way as 
not to introduce contaminants either during the 
sampling or during the determination of the C0 2 . 

Two very sensitive “relative” methods of C0 2 de¬ 
termination have been used, both of which require 
calibration and repeated standarization with mixtures 
of known C0 2 content. 







REMOVAL OF CO., BY MEANS OF SOLID ABSORBENTS 


201 


The Colorimetric Method 

"1 his method, developed early in the program 8 , de¬ 
pends upon the destruction by C0 2 of the color of 
a solution of the sodium salt of phenolphthalein. The 
method can be made very sensitive by a suitable 
choice of the concentrations of alkali and phenol¬ 
phthalein, and of the ratio of gas sample volume to 
reagent volume. The procedure consists in agitation 
of a sample of the air to be analyzed with a definite 
volume of the indicator solution, followed by a colori¬ 
metric measurement of the change in transmission so 
produced. The slope of the calibration curve, which 
is a plot of log transmission vs C0 2 content of the 
sample, is established by two points, one being the 
transmission of the original solution which has been 
carried through the manipulative procedure with a 
C0 2 -free gas, the other being the point obtained with 
a sample of gas of accurately known C0 2 content. 

Extensive use of this method has shown that it 
must be checked frequently, that it is often subject 
to unexplainable aberrations, and that it is capable of 
satisfactory precision only if considerable care is 
taken both in sampling and in carrying out the 
analysis. The data of Figure 19 were obtained by this 
method, and the scattering of the points is an indi¬ 
cation of the kind of results it is capable of when a 
series of samples of continuously changing C0 2 con¬ 
tent are taken. 24 

The Pfund Gas Analyzer 

Developed under Division 17, NDRC, the Pfund 
meter has proved to be completely satisfactory for 
the continuous analysis of exit gas samples. The 
instrument is very sensitive, gives rapid readings 
and, except for some uncertainty at low (15 ppm) 
concentrations of C0 2 , is capable of considerable 
accuracy. 19,20,21 This instrument utilizes the infrared 
absorption of C0 2 ; it has been described in Division 
17 reports. The setup in which the instrument was 
used is shown in Figure 14. The ascarite scrubber 
is used to supply the analyzer with a C0 2 -free 
sample for zero adjustment; when a reading is 
taken, the ascarite is bypassed (valve A closed, B 
open). 

Most of the analytical data reported were obtained 
with the Pfund gas analyzer. 

“Absolute” Methods 

Both the colorimetric method and the Pfund analy¬ 
zer are relative, and must be calibrated with a sample 
of known C0 2 content. Experience has shown that 


it is not safe to rely either upon the constancy of 
atmospheric air or upon known samples prepared 
by mixing C0 2 and C0 2 -free air in storage tanks for 
the required standard mixture. It was deemed pref¬ 
erable to devise a method, however elaborate, by 
which a standard source (for example, a tank of air) 
could be analyzed with accuracy, and to use this 
standard mixture for calibration of the relative 
methods. 

A number of experiments were carried out to ex¬ 
amine the possibilities of absorption on ascarite and 
weighing, and absorption in standard alkali, followed 
by back-titration. It was concluded that, with care 
and the observance of numerous precautions, ascarite 
can be used for samples of air containing 200 to 
400 ppm, but the errors introduced by traces of 
moisture and by the uncertainties of weighing ascarite 
bulbs weighing 50 to 100 g, could cause large inac¬ 
curacies. 24 The titration method, in which air was 
continuously passed through standard alkali and the 
excess alkali back-titrated, was very unsatisfactory. 

The method finally devised and adopted is a titra¬ 
tion method which avoids the errors introduced by 
exposure of the alkali to laboratory air, and by 
means of which a large sample can conveniently be 
taken, without necessitating the use of large and 
unwieldy sample containers. It consists of a sample 
bottle containing the standard alkali into which re¬ 
peated samples of the air to be tested can be drawn, 
each sample being removed by evacuation after ab¬ 
sorption of the C0 2 . The essential feature of the 
method is the titration without removing the sample 
of essential alkali from the reaction vessel. 24 

In connection with some studies started after the 
C0 2 absorption study was completed, this “absolute” 
method was modified to make the procedure simpler 
and to make the method applicable to very low C0 2 
concentrations. This modification consists in passing 
the air sample to be studied through a copper coil 
immersed in liquid air, at which temperature sub¬ 
stantially all of the C0 2 is condensed to a solid. 23 

The condensed C0 2 is allowed to expand, and is 
finally flushed into the titration vessel and titrated 
as in the method above. The volume of air sample 
that can be taken in this way is practically unlimited, 
the rate at which it can be taken being limited only 
by the heat transfer characteristics of the condensa¬ 
tion coil. 

As a numerical illustration of the quantities that 
are dealt with in this method, consider a sample of 
20 liters (20/28.3 ft 3 ) of air containing 300 ppm 




202 


AIR PURIFICATION 


110 V DC 



WOOL dryer ascarite scrubber 

riLTER (DRIERITE) 


Figure 14. Electrical and sampling setup for use with Pfund gas analyzer. 


C0 2 . This would consume about 27 cc of 0.02^ 
alkali. A 200-1 sample of air containing 30 ppm 
would consume the same amount of alkali. It is ap¬ 
parent that considerable precision is possible. 

9 - 4 - 2 Apparatus and Equipment for 
Absorption 

Air Supply 

For runs at pressures above atmospheric, the air 
was supplied by a Norwalk compressor capable of 
delivering about 100 scfm at 3,000 psi. The intake 
to this compressor was located in a duct which took 
air from a point about 70 ft above the ground. 


Bombs 

Early runs were made using a bomb which held 
about 7 lb of 4- to 8-mesh soda lime, and was 
charged in layers which could be separately re¬ 
moved and examined. It was soon found that the 
use of so large a charge was impracticable because 
the amount of air required could not be obtained 
when other units required air from the Norwalk 
compressor. Most of the work was carried out using 
the small bomb shown in Figure 15. This bomb 
held about 1 lb of soda lime, and runs could be made 
at linear velocities comparable to those expected in 
practice without using excessively large amounts of 
air. The small bomb was much more convenient to 
recharge and install. 


































































REMOVAL OF CO., BY MEANS OF SOLID ABSORBENTS 


203 



The Piping Arrangement 

The piping arrangement used for all the runs with 
the small bomb is shown in Figure 16. Essentially 
the same setup was used for the runs with the large 
bomb. 

The cooler in the inlet air line was generally 
maintained about 3 to 4 C below room temperature 
so that the air entering the absorbent was slightly 
under saturation. This was done to prevent the 
possibility of actual condensation of water in the 
absorbent bed. 


Apparatus for Low-Temperature Adsorption 

Experiments were made in a jacketed bomb in 
which the adsorbent was placed and through which 
the precooled test air was allowed to flow. The ar¬ 
rangement is shown in detail in the diagram of 
Figure 17. The exit and inlet air were analyzed 
by the Pfund analyzer. 

For reasons which will be given in a later section, 
a series of experiments were carried out at a temper¬ 
ature of —78.5 C (dry-ice) and at atmospheric 
pressure. 



















































































204 


AIR PURIFICATION 


TRAP 




3 . 


—X- 


? 


TRAP 



V 


COOLER 


X 


CJ 


SMALL 

BOMB 

WITH 

ABSOR-" 

BENT 


3 - 


inlet air sample 

'TO PF UN D ANALYZER 




EXIT AIR SAMPLE 
'TO PFUND ANALYZER 


-CX- 


EXIT 
l^J FLOWMETER 


GLASS WOOL 
FILTER 




TRAP 


BLEED OFF 
VALVE 


FLOW DIAGRAM 


Figure 16. Flow diagram for high-pressure absorption. 


Materials 

Soda Lime. The soda lime used was purchased from 
the Dewey and Almy Chemical Company, Boston, 
Massachusetts. It was obtained in two mesh sizes: 
4 to 8 and 14 to 20; and in high-moisture (16%), 
and low-moisture (less than 2%) grades. 

Soda lime is substantially a mixture of calcium, 
sodium, and potassium hydroxides; the material used 
in this work (Wilson soda lime) contains about 5% 
caustic alkalies, the remainder being calcium hy¬ 
droxide and a small amount of inerts (including 
some calcium carbonate). 

Potassium Hydroxide. The pellet grade, as com¬ 
monly used in chemical laboratories, and Niagara 
Alkali Works flake grade, were used. 

Sodium Hydroxide. Two forms of this were used : 
pellets, and a flake form furnished by the Wyandotte 
Chemical Company. 

Baralyme. Baralyme is a proprietary name used 
for a mixture of barium and calcium hydroxides 
[about 20% Ba(OH) 2 | manufactured by Thomas A. 
Edison, Inc., East Orange, N. J. 

Active Carbon. A number of active (gas purifica¬ 
tion) charcoals were obtained from commercial 
sources. These are identified in the section in which 
their testing is described. 

Others. A variety of active adsorbents other than 


active carbons were tested. These are described in 
the section in which their testing is described (see 
Table 1). 

9 4 3 Experimental Procedure 

Alkaline Absorbents 

A few early runs were made using the large bomb, 
which was installed at the same point as the small 
bomb shown in Figure 16. The soda lime was 
charged in eight layers of 0.845 lb each, separated 
by disks of copper gauze. In these runs the colori¬ 
metric method of C0 2 analysis was used. During 
the runs the inlet and exit air streams were analyzed 
at intervals for C0 2 and at the completion of a run 
the various layers of soda lime were removed sep¬ 
arately, sampled and analyzed for moisture and C0 2 
content. 

For reasons mentioned in an earlier section the 
large bomb was later discarded and all succeeding 
runs were made using the small bomb. In most of 
these runs no analyses of the exhausted charge were 
made. The inlet air stream was analyzed at inter¬ 
vals and, unless marked variations were observed, 
was assumed to remain substantially constant; ob¬ 
servations extending over many months have shown 
that the C0 2 content of the air taken into the roof- 











































REMOVAL OF CO, BY MEANS OF SOLID ABSORBENTS 


205 



AIR FROM COMPRESSOR 


Figure 17. Flow diagram and high-pressure sorption of carbon dioxide on charcoal. 






































































206 


AIR PURIFICATION 


level duct seldom varied outside the limits 320 to 
350 ppm. Exit air analyses were made sufficiently 
often to define clearly the slope and shape of the 
breakthrough curve. 

The flow rate was measured after expanding the 
air to atmospheric pressure. Readings were taken of 
the pressure and temperature points shown on the 
flow sheet (Figure 17). 


were made, no breakthrough curves were needed, 
and analyses of the exit and inlet air streams were 
made only for the purpose of recognizing when the 
adsorbent was saturated (that is, exit C0 2 concen¬ 
tration—inlet C0 2 concentration). When this point 
was reached, the adsorbent was allowed to warm up, 
and the desorbed C0 2 was collected on ascarite and 
weighed. 


Table 1. Adsorption of C0 2 from ordinary air at —78 C, atmospheric pressure.* 


Material 

T reatment 

Number 
of runs 

Adsorptionf 
grams C0 2 per g 

Silica gel 

Pumped out at 200 C, 2 hrj 

3 

0.0117 

Silica gel impregnated with Cr 2 0 3 § 

Heated at 300 C, 8 hr 

4 

0.0105 

CWSN 249 AY carbon 

As received 

2 

0.0081 

Silica gel 

As received 

1 

0.0080 

Silica gel impregnated with Cr 2 0 3 § 

Pumped out at 200 C, 2 hr$ 

1 

0.0069 

Activated alumina 

Pumped out at 200 C, 2 hr$ 

2 

0.0067 

Columbia 4ACW carbon 

As received 

3 

0.0065 

Columbia 6G carbon 

As received 

2 

0.0063 

CWSN 291 AY carbon 

As received 

1 

0.0063 

Activated alumina 

Heated at 180 C, 3 hr 

3 

0.0061 

CWSN 17-6 carbon 

As received 

1 

0.0060 

Silica gel impregnated with Cr 2 0 3 § 

Heated at 280 C, 4 hr 

1 

0.0057 

Pittsburgh C. and I. Company carbon 

Pumped out at 200 C, 2 hrj 

3 

0.0054 

Pittsburgh C. and I. Company carbon 

As received 

2 

0.0050 

Cr 2 0 3 (gel) 

Heated at 280 C, 4 hr 

1 

0.0032 

Cr 2 0 3 (precipitated) 

Dried at 150 C 

1 

0.0024 

Cr 2 0 3 (gel) 

Heated at 300 C, 2 hr 

2 

0.0008 

Fe 2 0 3 (precipitated) 

Heated at 300 C, hr 

2 

0.0003 


* Inlet air contained about 320 to 340 ppm C0 2 . 

t Saturation value. Runs continued at least 1 hr after analyses showed C0 2 concentration in exit air r= C0 2 concentration in inlet air. 

t Samples pumped out at full vacuum of Hy-vac pump. 

§ Contained about 9 % by weight of Cr 2 0 3 . 

Adsorption at Low Temperature 

At 3,000 psi, The precooled air stream was passed 
through the adsorbent, the temperature of which was 
maintained entirely by the air passing through it and 
measured by inlet and outlet thermocouples. The 
air was expanded through a reducing valve and the 
flow measured at atmospheric pressure. The C0 2 
content of the inlet and exit air streams was measured 
frequently by means of the Pfund analyzer. At the 
completion of a run (that is, when complete break¬ 
through was observed) the adsorbent was allowed 
to warm up slowly, the desorbed C0 2 being absorbed 
in tared ascarite bulbs and weighed. 

At Atmospheric Pressure. For the purpose of ob¬ 
taining a rapid comparison of a number of adsorbents, 
the experimental difficulties involved in regulating 
and maintaining accurate temperature control in the 
high-pressure unit were avoided by carrying out a 
series of runs using air at ordinary pressure, and 
cooling the adsorbent in a bath of acetone-dry ice 
(Figure 18). For the purposes for which these runs 


In all cases, duplicate runs were carried out when¬ 
ever there was any question as to the validity of the 
results or when, for any reason, considerable changes 
in operating conditions (flow, temperature, pressure, 
etc.) occurred during a run. In some series of experi¬ 
ments all runs were made in duplicate. 

9 4 4 Experimental Results 

Alkaline Absorbents 

Low-Moisture Soda Lime. A series of nine runs 
(TC 13-22) were made with 4- to 8-mesh, low-mois¬ 
ture (2%) soda lime. A charge of 1 lb was used in 
the small bomb (about 13-in. bed depth) and flow 
rates of 400 to 1,600 scfh (at 3,000 psi) were chosen. 

These runs were started with the original inten¬ 
tion of determining the effect of flow rate upon the 
initial slope of the breakthrough curve, and were later 
extended for longer durations when the surprising 
observation was made that, after a certain period of 
operation, the efficiency of the partiallv exhausted 







REMOVAL OF CO, BY MEANS OF SOLID ABSORBENTS 


207 


absorbent increased (that is, amount of breakthrough 
decreased). The experimental data and a plot of the 
percentage of C0 2 not removed are given in Figure 
19. This quantity is used in most of the plots which 
present the original data and is the ratio [(ppm C0 2 
in exit air / ppm CO, in inlet air) X 100] vs total air, 
scf per lb of soda lime. 


analyses in these runs were carried out by the use 
of the colorimetric method it cannot he said with 
certainty that the differences in the initial portions of 
the curves of Figure 19 are significant. It is quite 
possible that, over the range of flow rates studied, all 
of the data up to total air flows of 500 scf per lb fall 
on a single line.) The important conclusion to be 


sample holder: 1/2"-pipe 

SIZE COPPER TUBING, WOUND 
WITH 1/4" COPPER TUBING 



Figure 18. Flow diagram for atmospheric pressure absorption runs. 



Figure 19. Breakthrough curves for low-moisture soda lime. 


It is seen that for flow rates of 1,000 scfh per lb 
and over, all the points fall on one curve. For lower 
flow rates, down to 400 scfh per lb, the curves have 
about the same initial slopes as at higher flow rates, 
but reach their maximum sooner. (Since the CO L > 


drawn from these data is that even at relatively low 
flow rates (400 scfh per lb of soda lime, or 135 scfh 
per sq in. bed area) low-moisture soda lime permits 
rapid and extensive breakthrough, and at no time in 
its life does it remove all of the CO a from the air. 




























208 


AIR PURIFICATION 



It is of interest to note that the point at which the 
minimum in any curve of Figure 19 is reached de¬ 
pends upon the total height of the curve (or upon 
the position of the maximum). 

A reasonable explanation both for this observation 
and for the general shape of these curves has been 
adduced from a consideration of the mechanism of 
the soda lime-CCb reaction. 

High-Moisture Soda Lime. Runs made using 
high-moisture soda lime fall into several distinct 
groups. The first seven runs were made using 4- to 
8-mesh material in the large bomb. Succeeding runs 
were made using the small bomb, and fall into several 
groups. The results of these runs are largely incon¬ 
clusive, and are presented in Figure 20. It was in an 
attempt to extend these runs that the low-moisture 
soda lime runs were made. 

Of greater interest are two other sets of data taken 
in these experiments. These are derived from chemi¬ 
cal analyses of the various layers removed from the 
bomb, and afford some information regarding the 


progress through a bed of tbe zone of exhausted ab¬ 
sorbent and tbe water relationships involved in the 
use of high-moisture soda lime. 

In Figure 21 are shown the results obtained by 
analyzing the separate layers for C0 2 content. It is 
observed that at the lowest flow rate used (Run A-l; 



(OUTLET) NUMBER OF LAYER (INLET) 


Figure 21. Capacity of high-moisture soda lime. 














REMOVAL OF CO. BY MEANS OF SOLID ABSORBENTS 


209 


30 scfh per lb) a sharp “front" exists in the bed. In 
run B-2, which was discontinued when 96% of the 
inlet C0 2 was still being absorbed, the outlet layer is 
beginning to be used up while none of the other layers 
is yet completely exhausted. Runs A-2, A-3, and B-l 
were unfortunately continued too long and the re¬ 
sults are inconclusive. 

It is evident that only at very low rates of flow 
does a sharp concentration front exist in a soda lime 
bed, and it is also apparent that even extensively 
exhausted material can still function at high efficiency 
providing a low flow rate is used. 

Water Relationships 

A great deal of water is liberated in the reaction 
between soda lime and C0 2 . The overall reaction 
may be written 

Ca(0H) 2 + C0 2 ^CaC0 3 + H 2 0. (1) 

For every 100 g of soda lime, 16.8 g of water is pro¬ 
duced, for 90% exhaustion. The fate of this water 
is of practical importance in the use of soda lime. 
The water formed cannot be carried off in the exit 
air because the inlet air is saturated, or nearly so. It 
will thus remain in the bed, or in the bomb, or be 
carried over by entrainment. 

It is apparent that in the use of soda lime for the 
cleanup of high-pressure air, the system must be so 
designed that the large amount of water evolved in 
the reaction cannot escape into the exit lines leading 
to other parts of the unit. Suitable traps or dead 
spaces in the soda lime vessels must be provided. 

It should also be emphasized that drying systems 
devised for use in a system in which soda lime is used 
must be designed to handle air which is saturated 
with water. It has been shown in the preceding para¬ 
graph that to attempt to shift part of the drying load 
to the soda lime by the use of the low-moisture grade 
will result in imperfect C0 2 removal. 

Small Bomb Total Cleanup Runs 

The log-log plot has proved the most suitable 
method of plotting data such as these, since experi¬ 
ence has shown that the initial rise in exit concen¬ 
tration follows a straight line, thus allowing aber¬ 
rations and inconsistencies in the data to be recog¬ 
nized. 

In order to use the log-log plot, however, one ar¬ 
bitrary assumption had to be made for convenience 
in plotting; this is that the breakthrough point (C0 2 


just appearing in the exit stream) is equivalent to 
“1% not removed" (99% cleanup). Since this value 
represents an actual exit C0 2 concentration of 3 to 
4 ppm it is about the smallest amount that the meth¬ 
ods of analysis can detect with certainty. (See Fig¬ 
ure 22.) As an example of the usefulness of this 
way of presenting the data, consider operation at 
600 scfh per lb; C0 2 will begin to appear in the exit 
stream after 5.1 hr of operation. At 200 scfh per lb 
cleanup will be complete for 29 hr. Thus, assuming 
a fixed flow rate, the use of three times as much soda 
lime will permit six times the operating life. 



Figure 22. Capacity of high-moisture soda lime. 


The advantage of operating at low flow rates de¬ 
creases as the tolerance for C0 2 in the exit stream 
increases. For example, if operation can be contin¬ 
ued until 10% of the inlet C0 2 is appearing in the 
exit stream, 600 scfh per lb will allow operation for 
9 hr, while 200 scfh per lb will allow operation for 
33 hr. In Figure 23 are shown curves which repre¬ 
sent comparisons of this sort over a range of C0 2 
tolerance and flow rates. The results are plotted as 
relative efficiencies, comparisons being made to 200 
scfh per lb. For example, to operate to initial break¬ 
through with a flow of 800 scfh per lb a run of 2.2 hr 
can be made; at 200 scfh per lb a run of 29 hr, an 
advantage of 13.2 in relative times. If 800 scfh per 
lb were as efficient as 200 scfh per lb the lower flow 




210 


AIR PURIFICATION 


rate would permit operation for only four times as 
long a period. Thus, 


Relative efficiency of 200 scfh per lb over 800 scfh 

per lb = X 100 = 340%. (2) 

4 

From Figure 23 it can be seen that the smaller the 
ratio of high flow to low flow the lower is the relative 
efficiency, and the greater is the amount of C0 2 that 
can be tolerated in the excess air. 


500 



DEWEY AND ALMY SODA LIME 
4-8 MESH, HIGH MOISTURE 
RELATIVE EFFICIENCY OF 
OPERATING AT 200 SCFH 
PER LB AND FLOWS OF 800, 
600 AND 400 SCFH PER 
LB VS % INLET C02 IN 
EXIT AIR 

PRESSURE , 3000 PSI 

TEMPERATURE, 23C 


200 VS 200 


0 10 20 30 

PER CENT OF INLET C0 2 PERMITTED IN EXIT AIR 


Figure 23. Relative efficiency of high-moisture soda lime 
at various flows. 


Effect of Mesh Size 

14- to 20-mesh soda lime is markedly more effec¬ 
tive than 4- to 8-mesh material particularly at higher 
flow rates. The difference between them would be 
expected to be smaller the lower the flow rate, since 
in the limit, at an infinitely low rate, they would be 
equal in effectiveness. 

Since, as will be shown later, low linear velocities 
should be used for maximum efficiency in the utili¬ 
zation of soda lime, and the pressure drop through 
a bed operating at 3,000 psi is inconsiderable, it is 
clear that 14- to 20-mesh soda lime is definitely to 
be preferred to 4- to 8-mesh material. The holdup 
and entrainment of water would be expected to be 
greater in the bed of smaller mesh material, and this 
fact should be recognized in the design of the cleanup 
system. 

Direction of Flow through the Absorbent 

Runs were performed with the direction of flow 
downward through the bed; these runs are compared 


in Table 2, with the runs described in the preceding 
section in which the flow was upward through the 


bed. 


Table 2 




Total flow, scf per lb, to 


Flow, 

3% 

10% 

Direction of flow 

scfh per lb 

breakthrough 

breakthrough 

Bottom to top 

800 

4,750 

5,200 

Top to bottom 

800 

4,200 

5,900 

Bottom to top 

1,200 

4,500 

5,400 

Top to bottom 

1,200 

3,800 

4,800 


All runs on 14- to 20-mesh, high-moisture soda lime 


It is seen that there is a small but definite advan¬ 
tage in operating with the flow upward through the 
bed. This is probably due to the fact that water drain¬ 
ing from the soda lime is held in the bed, whereas in 
downward flow it is continuously removed. It is to 
be remembered that this water is in reality a solution 
of alkali hydroxides which are leached from the soda 
lime particles. Removal of this water leaves alkali- 
deficient soda lime; and its scrubbing action when 
held in the bed certainly contributes to the C0 2 re¬ 
moval from the air being treated. 

It can be concluded further from these considera¬ 
tions that a properly designed cleanup system would 
include some provision for the air to be scrubbed by 
the liquid draining from the bed before it entered the 
soda lime itself. Perhaps a suitable arrangement 
would be one in which a short section packed with 
some inert contact material (for example, Berl 
saddles) would be provided below the soda lime 
section, forming a short scrubbing tower in which 
the draining liquid could collect. 

Linear Velocity Studies 

A limited amount of work was done in an attempt 
to determine the effect of linear velocity on the effi¬ 
ciency of 4- to 8-mesh soda lime at constant space 
velocity. The results are not entirely concordant and 
are too scanty to permit significant conclusions being 
drawn. The breakthrough curves are plotted in 
Figure 24. 

It appears that a certain value of linear velocity 
(0.03 to 0.05 ft per sec) must be reached before 
maximum effectiveness is obtained, and that a further 
increase offers no advantage. The data are too 
meager to allow much more to be said, and circum¬ 
stances prevented an extension of this line of at¬ 
tack at the time. 












REMOVAL OF CO_, BY MEANS OF SOLID ABSORBENTS 


211 



TOTAL AIR , SCF PER LB 


Figure 24. Effect of linear velocity on breakthrough. 


“Life” Tests 

“Life” is an arbitrary concept, depending upon the 
service for which the cleanup system is used. Here 
it is defined as the number of hours of operation 
which can be realized before the exit air contains 3% 
of the C0 2 concentration of the inlet air (with ordi¬ 
nary air, this critical concentration is 10 ppm C0 2 ). 
The critical bed length is a concept originally em¬ 
ployed in studies on the adsorption of toxic gases on 
active adsorbents; in the present work it is defined 
as that length of adsorbent necessary, under given 
conditions of flow, temperature, pressure, and bed 
area, to reduce an entering concentration (C 0 ) of a 


contaminant (C0 2 ) to an arbitrarily chosen exit con¬ 
centration (Ce = 10 ppm). 

For the ends to which these studies were directed 
the runs at 3,000 psi are of the greater practical im¬ 
portance ; the series of runs at 1 to 2 atm were made 
as a preliminary to the high-pressure runs and for 
the purpose of determining whether the methods of 
correlating results were applicable in both pressure 
ranges. 

Life Runs at 1 to 2 Atmospheres. A series of runs 
were made at pressures corresponding to the pres¬ 
sure drop through the system with no exit throttling 
other than that provided by the flowmeter orifice. In 








212 


AIR PURIFICATION 


general this amounted to around 10 psi. The absor¬ 
bent was 14 to 20 mesh ; high-moisture soda lime and 
the small bomb were used. 

These data were of interest in checking the validity 
of certain correlations of the data obtained in high- 
pressure runs; if such correlations hold for results 
obtained under two widely disparate sets of condi¬ 
tions they can be regarded with added confidence. 

The low-pressure runs were made at three flow 
rates: 200, 400, and 600 scfh, and for each flow rate 
a series of runs with varying amounts of absorbent 
(that is, different bed length) were made. 

In Figure 25 are plotted life-thickness curves for 


In Figure 26 is plotted F/L c vs F -0 - 59 ; it is seen 
that a straight line results. In Table 3 are given L c 
values derived from Figure 26, those for 200, 400, 
and 600 scfh being the experimental values. 


Table 3 


F, scfh 

Lr, ill. 

100 

1.3 

200 

1.0 

400 

2.8 

600 

3.5 

800 

4.2 

1,000 

4.9 



these flow rates, life being defined as hours to 3% 
breakthrough. 

Studies in Division 10, NDRC (Klotz, OSRD re¬ 
port No. 3774), have shown that in the adsorption 
of toxic gases on charcoal the following relationship 
exists between linear velocity and critical bed length. 

— = KF-°™ -f Ki. (3) 

Fc 

F = flow rate (proportional to velocity) 

L c = critical bed length 


Life Runs at 3,000 psi. The life-thickness curves 
are plotted in Figure 27 (in which are included 
derived curves for 100, 800, and 1,000 scfh, with 
single data points for 100 and 1,000 scfh). 

In Figure 28 are plotted critical bed lengths and 
pseudo-critical bed lengths vs flow rate. The pseudo- 
critical bed length is of somewhat greater usefulness 
than the true critical bed length, and is the intercept 
on the length axis of the straight-line portion of the 
life-thickness curve. 







REMOVAL OF CO, BY MEANS OF SOLID ABSORBENTS 


213 


DEWEY AND ALMY SODA LIME 
HIGH MOISTURE, 14-20 MESH 
■COW PRESSURE (10 PSI) 

RUNS 1.94" I D BED 



Figure 26. Effect of flow rate on critical bed length. 


Slope of the Life-Thickness Curve 

The slope of the life-thickness curve is in the units, 
hours of life per inch of bed length. Thus it repre¬ 
sents capacity of the soda lime, and if breakthrough 
always occurred at the same degree of exhaustion of 
the soda lime, the slope should be inversely propor¬ 
tional to flow rate. In Figure 29 are plotted the 


slopes of the straight-line portions of the curves 
of Figure 27 vs flow rate. It can be seen that at 
low flow rates the slope of the curve approaches 
minus one, but at higher rates it deviates consider¬ 
ably, indicating that the soda lime is utilized less 
efficiently at high rates of flow. 

It is easy to calculate the position of the ideal curve 
shown as a dotted line in Figure 29, knowing the 
density and theoretical capacity of soda lime, as 
follows: 

Slope of life-thickness curve (hr per in.) 


= density X capacity X — » (4) 


where density = lb soda lime per in. 3 = 53.5/1,728 
capacity rr scf air per lb soda lime = 12,000 
F = scfh per sq in. bed area; 

then 


slope = life (hr per in.) 


53.5 X 12.000 _ 372 
1,728 F ~ F 


Referring to Figure 29, it can be seen that the ideal 
curve shows life of 3.7 hr per in. at F = 100, ex¬ 
actly as the above calculation predicts. 



BED LENGTH IN INCHES 


Figure 27. Life thickness curves. 








CRITICAL BED LENGTH, 'INCHES 


214 


AIR PURIFICATION 


DEWEY 8 ALMY SODA LIME 
HIGH MOISTURE, 14*20 MESH 
3000 PSI * 20 C 
ATM AIR USED 

L c ' : "PSEUDO" CRITICAL BED LENGTH 
L c = CRITICAL BED length 



FLOW Rate, scfh per sq in.of bed area 


Figure 28. Pseudo-critical bed length. 



The actual curve deviates from the ideal in a way 
that cannot be given a simple mathematical expres¬ 
sion. It has been found that an approximation can 
be made which expresses the facts with reasonable 
accuracy (ca 5%) by considering the actual curve 
to consist of two straight lines of different slopes, 
intersecting at F = 100. The equations of these 
curves are: 

For F = 0 to 100 scfh per sq in., 

/310V- 07 

life (hr per in.) = (——J . (5) 

For F = 100 to 300 scfh per sq in., 

/200 V- 69 

life (hr per in.) = • (6) 

The plot of Figure 30 is of further assistance in 
extrapolating the data. In this are plotted flow rate 
vs the lengths of bed required for a life of 10, 6, 4, 
2. and 1 hr, respectively. 

In Figure 32 are plotted life-thickness curves simi¬ 
lar to those of Figure 28. It shows life-thickness 
curves with a greatly extended scale (up to 120 hr 
life and 18 ft of bed length). 

It is not certain that extension of the data to such 
long bed lengths as in Figure 31 is entirely justifiable 
for high flow rates. It is, however, felt that reliance 
can be placed on this extrapolation for flows of 200 
scfh per sq in. of bed area, or less. In any case, the 
values of life as chosen from a plot such as Figure 31 
will be conservative; that is, a bed designed to last, 
say, 50 hr, will last at least that long (to 3% break¬ 
through). 

The plot of Figure 32 was derived from the ex¬ 
tended life-thickness curves of Figure 27. From this 
plot can be obtained the bed length necessary for 
operation for any required period, at a given flow 
rate. 

The most striking conclusion to be drawn from the 
plots is that operation at a low linear velocity sharply 
increases the efficiency of utilization of the soda lime. 
For example, in a unit using a total air feed of 
6,000 cfh (70 F), the use of a Harrisburg-type bomb 
(9.5-in. ID) allows about 85% of the total capacity 
of the soda lime to be used before 3% breakthrough, 
whereas the use of a 4.5-in. ID bomb allows only 
29% of the total capacity to be utilized to the same 
point. 

1 his result is to be expected from the observation 
noted in the preceding paragraph that the slope of 


Figure 29. Effect of flow rate on life thickness. 









REMOVAL OF CO, BY MEANS OF SOLID ABSORBENTS 


215 



the life-thickness curve is inversely proportional to 
the flow rate at very low flows, but becomes in¬ 
versely proportional to an increasing power of the 
flow rate at higher flow rates. 

Other Absorbents 

In Figure 33 are plotted the results of a series of 
runs on several other absorbents: Wyandotte flake 
NaOH (TC51); Niagara flake KOH (TC 65); 
Fisher pellet KOH (TC 52); Fisher pellet NaOH 
(TC 53). 

It is clear that 4- to 8-mesh soda lime is superior 
to any of these, and it can safely be assumed that 


14- to 20-mesh soda lime would be greatly superior 
to any. 

Baralyme. This is a proprietary name for a 
composition of 20% Ba(OH) 2 • 8H 2 0 and 80% 
Ca(OH) 2 . It was tested at 3,000 psi, and found to 
be very inefficient under these conditions, being far 
inferior even to 4- to 8-mesh high-moisture soda 
lime. It can be concluded that soda lime, under the 
conditions used, particularly the 14- to 20-mesh high- 
moisture grade, is superior to any other alkaline ab¬ 
sorbent studied. The reason for the relative inef¬ 
fectiveness of KOH and NaOH may lie in the 
water relationships involved. 24 








216 


AIR PURIFICATION 



Figure 31. Expanded life thickness curves. 


Moisture Content 

The most illuminative series of runs in this con¬ 
nection were on low-moisture soda lime (Figure 19). 

The very dry low-moisture material allows about 
the same initial breakthrough for all flows from 400 
to 1,600 scfh per lb. As the runs continue, however, 



Figure 32. Bed length flow rate data. 


water is formed and the soda lime becomes increas¬ 
ingly wetter. By the time the soda lime has become 
wet enough to attain maximum activity, however, it 
has absorbed a considerable amount of C0 2 and thus 
the curves never return to 100% removal and soon 
begin to climb towards complete exhaustion. 

It can be seen from Figure 19 that the point at 
which the minimum is reached depends upon the 
total height of the curve. This means that in a run 
in which (because of a high flow rate) the stripping 
of C0 2 is quite incomplete, the amount of reaction to 
form water is likewise cut down so that a longer 
period of running is necessary to form the water 
necessary for maximum activity of the sodium hy¬ 
droxide film. 

The degree of exhaustion of the soda lime affects 
the overall rate of the reaction. This is shown by 
the fact that a group of breakthrough curves for 
different flow rates come together and become sub¬ 
stantially coincident after 60 to 70% of the inlet 
C0 2 has passed through the bed. 

The effect of the C0 2 concentration of the air 
being treated is shown by the curves of Figure 34. 





REMOVAL OF CO., BY MEANS OF SOLID ABSORBENTS 


217 


V TC4I HIGH MOISTURE SODA LIME 

(DEWEY 8 ALMY 4-8 MESH) 
♦ TC5I WYANDOTTE FLAKE 

SODIUM HYDROXIDE 

O TC52 FISHER PELLET POTASSIUM 
HYDROXIDE 

<t> TC53 FISHER PELLET 

SODIUM HYDROXIDE 

X TC65 NIAGARA FLAKE KOH 



Figure 33. Break through curves for various absorbents. 



120 

— i—i—i—i—i i i r 

Q 



IaJ 

> 

too 

_ DEWEY AND ALMY SODA LIME — 

o 

4-8 MESH, HIGH MOISTURE 

2 

Ui 


EFFECT OF INLET C02 

sr 

80 

CONCENTRATION ON BREAKTHROUGH — 


AT 800 SCFH PER LB SODA LIME 

o 

z 

60 

PRESSURE , 3000 PSI 

TEMPERATURE, 23C — 

o 

o 

h- 

TC 33 A A 

UJ 

40 

— 445 PPM C0 2 pS — 

z 


qXTA DIESEL 

u_ 

20 

</T \ SHUTDOWN 36 

o 

— ^ \ 10 MIN 370- 390 PPM C02 

i 5 

O 

/\ 1 1 1 1 


0 <f I _t -1-1-1 - 1 - 1 - 

0 I 2 3 4 3 6 7 8 X I0 5 


TOTAL AIR, SCFH PER LB 

Figure 34. Effect of C0 2 concentration on break¬ 
through. 

methods of temperature maintenance and control 
were chosen so as to simulate conditions which 
might be encountered if such a cleanup system were 
to be used on the Keyes unit (Chapter 4). 

A series of runs on Columbia 4 ACW charcoal, 
6 to 14 mesh, were made at different temperatures. 
The results of these runs are tabulated in Table 4. 

It is apparent from these data that the saturation 
capacity of the charcoal is low and that rapid break¬ 
through occurs. 


Table 4 


Adsorbent: Columbia 4 ACW charcoal, 6 to 14 mesh. 
Bed size: 0.953 in. ID by 10 in., containing 53.2 g charcoal. 


Run number 

9 

8 

10 

Bed temperature F 

- 103 

- 147 

- 211 

Flow, cfh (60 F, 1 atm) 

39.3 

39.7 

41.0 

Pressure, psi 

2,450 

2,500 

2,500 

Saturated adsorption, g CCk per g charcoal 
From adsorption data 

0.0043 

0.0052 

0.0080 

By desorption 

0.0030 

0.0057 


Inlet CO 2 ppm 

320 

325 

340 

Max temperature on desorption, F 

Top of bed 

- 79 

- 80 

— 76 

Bottom of bed 

- 21 

- 9 

- 16 


These represent two runs made under identical con¬ 
ditions except for the higher C0 2 content of the 
inlet air in one run. It appears that in this case a 
transitory saturation of the surface of the particles 
has taken place, disappearing when added water is 
formed. 

9.4.5 Adsorption of C0 2 on Active Ad¬ 
sorbents at Low Temperature 

Adsorption at 2,000 to 3,000 psi 

The apparatus shown schematically in Figure 17 
was used. This arrangement of apparatus and the 


Run 13, using 104.2 g of activated alumina, with 
a bed temperature of —147 F at 2,500 psi and 45.6 
cfh flow, showed complete adsorption for 20 min 
followed by steadily increasing breakthrough. The 
saturation capacity of the alumina was found to be 
0.0142 g C0 2 per g. This is about three times the 
capacity of the Columbia 4 ACW carbon. As will be 
shown below, however, it is still low as far as prac¬ 
tical usefulness is concerned. 

Runs were made at —147 F, 3,000 psi, and about 
40 to 45 cfh, using two other commercial charcoals. 
The saturation capacities are given in Table 5; a 
typical breakthrough curve is shown in Figure 35. 














218 


AIR PURIFICATION 


PRESS 3000 PSI FLOW 42.9 SCFH 

TEMP - 147 F RUN NO. 16 

CARBON CWSN 249 AY 



Figure 35. C0 2 absorption on activated carbon. 


to make a rapid survey of a large number of sub¬ 
stances. 

Besides the various commercially valuable adsorb¬ 
ents on band, the following materials were prepared. 

Chromium Oxide. Two samples of this were made, 
one of which was clearly a gel, the other, duller in 
appearance, probably not gel-like in structure. 

Chromium Oxide on Silica Gel. This is prepared 
by impregnating silica gel with chromium nitrate and 
precipitating the hydroxide in situ, followed by dry¬ 
ing and heating. 

Ferric Oxide. This is precipitated, dried, and 
heated. 


Table 5 

Adsorbent used: CWSN 249AY : 117 cc ; 38 g 
Columbia 6G: 117 cc; 52.5 g 

Bed temperature : —147 F ; pressure 3,000 psi; inlet air 325 ppm C0 2 - 


Saturation capacity, g C0 2 per g carbon 


Run No. Carbon 

From ads data 


By desorption 

16 CWSN 249AY 

0.0046 


0.0053 

17 

0.0046 


(0.0035) 

18 

0.0053 


0.0066 

19 Columbia 6G 

0.0059 


0.0058 

20 

0.0047 


0.0053 

22 “ 

0.0043 


0.0054 

24 Pittsburgh C. & I. 

0.0067 



Table 6. Adsorption of C0 2 from ordinary air at —78 C, atmospheric pressure.* 



Number 

Adsorptioiff 

Material 

T reatment 

of runs 

grams C0 2 per g 

Silica gel 

Pumped out at 200 C, 2 hr$ 

3 

0.0117 

Silica gel impregnated with Cr 2 0 3 § 

Heated at 300 C, 8 hr 

4 

0.0105 

CWSN 249 AY carbon 

As received 

2 

0.0081 

Silica gel 

As received 

1 

0.0080 

Silica gel impregnated with Cr 2 0 3 § 

Pumped out at 200 C, 2 hr$ 

1 

0.0069 

Activated alumina 

Pumped out at 200 C, 2 hrj 

2 

0.0067 

Columbia 4ACW carbon 

As received 

3 

0.0065 

Columbia 6G carbon 

As received 

2 

0.0063 

CWSN 291 AY carbon 

As received 

1 

0.0063 

Activated alumina 

Heated at 180 C, 3 hr 

3 

0.0061 

CWSN 17-6 carbon 

As received 

1 

0.0060 

Silica gel impregnated with Cr 2 0 3 § 

Heated at 280 C, 4 hr 

1 

0.0057 

Pittsburgh C. and I. Company carbon 

Pumped out at 200 C, 2 hrj 

3 

0.0054 

Pittsburgh C. and I. Company carbon 

As received 

2 

0.0050 

Cr 2 0 3 (gel) 

Heated at 280 C, 4 hr 

1 

0.0032 

Cr 2 0 3 (precipitated) 

Dried at 150 C 

1 

0.0024 

Cr 2 0 3 (gel) 

Heated at 300 C, 2 hr 

2 

0.0008 

Fe 2 Os (precipitated) 

Heated at 300 C, hr 

2 

0.0003 


* Inlet air contained about 320 to 340 ppm C0 2 . 

t Saturation value. Runs continued at least 1 hr after analyses showed CO. concentration in exit air = CO., concentration in inlet air, 
t Samples pumped out at full vacuum of Hy-vac pump. 

§ Contained about 9% by weight of Cr 2 O r 


Low-Pressure Adsorption at — 78 C 

In view of the expenditure of time and materials 
necessary to complete successful high-pressure runs, 
a series of comparison runs were made at —78 C and 
atmospheric pressure. By this means it was possible 


In Table 6 are given the results obtained, arranged 
in order of decreasing effectiveness. It is noteworthy 
that the saturation values obtained under these con¬ 
ditions are almost the same as those obtained at 
3,000 psi and —145 F. 















REMOVAL OF CO, BY MEANS OF SOLID ABSORBENTS 


219 


Examination of the values in Table 6 shows that 
most of the adsorbents tested are of about the same 
order of effectiveness. Silica gel appears to be the 
best from the standpoint of weight but it was not 
considered sufficiently superior to warrant the ex¬ 
penditure of time necessary to examine its break¬ 
through characteristics. 

If certain assumptions are made, it is possible to 
estimate how much better an adsorbent has to be 
than those already tested in order for it to be of 
potential usefulness for the removal of C0 2 in a 
unit such as the Keyes unit. Taking run 16 (Table 
5) as typical for active carbon, it is seen that break¬ 
through occurred almost at once and the carbon was 
saturated after about 40 min. In this run a space 
velocity of about 10.000 hr -1 (scfh per cu ft carbon) 
was used. The breakthrough curve for run 16 is 
reproduced approximately as curve 05, Figure 36. 

CURVE OB: RUN 16; CARBON CWSN 
249 AY 

CURVE DC: HYPOTHETICAL ADSORBENT, 
POTENTIALLY OF 
PRACTICAL VALUE 



TIME IN MINUTES 

Figure 36. Time breakthrough curves. 

Use of Data 

The following will be assumed: (1) In a Keyes 
unit, the same space velocity will be used (2) with 
complete C0 2 removal, and (3) an adsorbent better 
than the carbon used in run 16 will show its super¬ 
iority in increased time to initial breakthrough; that 
is, the slope of its breakthrough curve will not be 
less than that in run 16. Such an adsorbent would 
have the hypothetical breakthrough curve DC in 
Figure 36. 

Referring to Figure 36, the total capacity of the 
carbon of curve OB is represented by the area CAB 
= 6.5 units. The total capacity of the absorbent of 
curve DC is represented by the area OACD = 32.5 
units, five times the area OAB. 

Thus it is seen that for an adsorbent to be worthy 


of consideration for use under the conditions speci¬ 
fied above, it must have at least five times the ca¬ 
pacity at saturation as the carbon of run 16 (CWSN 
249 AY). Since it is probable that assumption (3) 
above is very conservative, it seems likely that an 
adsorbent must be well over five times better (in 
saturation capacity) than CWSN 249 AY to be 
operable under the conditions chosen. Since an ad¬ 
sorbent would tend to become less efficient on re¬ 
peated cycling, it would probably be safer to assume 
that an adsorbent must be nearer ten times better 
than CWSN 249 AY to be satisfactory. 

This calculation is admittedly an approximation 
but it furnishes the best basis upon which to answer 
the question: How can saturation values be used 
in selecting adsorbents of potential usefulness? It is 
clear that none of the adsorbents so far tested 
approaches the standard deemed necessary. 

There is one further point which must be consid¬ 
ered before discarding such adsorbents as the heavy 
metal oxides on the basis of low-pressure tests alone. 
One of the reasons for the low capacity of carbons at 
3,000 psi may be the saturation of the active surface 
by nitrogen and oxygen. Unless C0 2 has a high 
preferential affinity for the adsorbent it is adsorbed 
to a small extent only. It was thought that metallic 
oxides, by virtue of a chemical combination rather 
than a physical adsorption, might show a high pref¬ 
erential adsorption of C0 2 . This point is still unset¬ 
tled at high pressures, but at low pressures no such 
preference is shown. In view of the requirements 
of a good adsorbent it was not deemed promising to 
pursue this point in more detail. 

It can be concluded that no adsorbent has been 
found which is worthy of consideration for C0 2 
cleanup in an operating unit of the Keyes high- 
pressure type. 

9 4 6 Deposition of Carbon Dioxide from 
Air Streams by Direct Cooling 

No information was available on the character¬ 
istics of solid carbon dioxide as precipitated from air 
streams. In the development of low-pressure oxygen 
producing units (Chapters 2 and 3) it was found 
possible to precipitate solid C0 2 at low temperatures 
and to evaporate the solid by reversing stream flows 
in a suitable manner. High-pressure units (see Chap¬ 
ter 4) were developed where the C0 2 was precipi¬ 
tated and removed from the air stream by filtration. 
Also, it was suggested 18 that the C0 2 content of sub¬ 
marine air could be controlled by precipitation of C0 2 





220 


AIR PURIFICATION 


by refrigeration. In all three applications it was 
necessary to obtain basic information on the equilib¬ 
rium between solid and gaseous C0 2 and on the 
mechanisms involved in the precipitation and evapo¬ 
ration of C0 2 . 

Equilibrium between Solid C0 2 and 
Gaseous CCX-Air Mixtures 

In the design of air liquefaction-rectification equip¬ 
ment in which C0 2 removal is accomplished by con¬ 
densation of the C0 2 as a solid it is important to 
have accurate data on the saturation concentrations 
of C0 2 in air over a wide range of temperature and 
pressures. 

The use of existing data and known equations of 
state, such as van der Waals, Beattie-Bridgman, 24 
is of value only under conditions which do not too 
closely approach those of the critical state; and the 
approximations made by assuming Dalton's law to 
hold (that is, that the mixtures are ideal) are only 
roughly valid at relatively low pressures and tempera¬ 
tures which are not too low. The conditions at which 
data are required (temperature below —100 C, pres¬ 
sure over 40 atm.) are beyond the range of validity of 
the fugacity rules of Lewis and Randal, using the 
van der Waals constants; and when the non-ideality 
of air only is taken into account by the use of New¬ 
ton’s empirical method the results are little better. 

Calculations have been made using an adaptation 
of the method developed by Goff and Gratch, making 
use of a modified form of the Beattie-Bridgman equa¬ 
tion, together with interaction constants whose forms 


were predicted by statistical mechanics. These calcu¬ 
lations were far more successful than the van der 
Waals treatment. 23 

The applications of this technique are capable only 
of giving approximate indications of the order of 
magnitude of the deviations from Dalton’s rule, and 
cannot be accepted for quantitative predictions to be 
used in the design of apparatus; they would have to 
be substantiated by experimental results. Since the 
calculated magnitude of the deviations seemed to be 
quite large in some cases, it was clear that it would be 
of great practical importance to study experimentally 
the saturation concentrations of C0 2 in air. These 
investigations would also be of extreme fundamental 
importance, since the available data on the property 
of gaseous mixtures are quite limited, so that addi¬ 
tional data would be valuable for the future develop¬ 
ment of the theory of gaseous mixtures. 

Analysis and Apparatus. The general principles of 
the method for C0 2 analysis have been described in 
preceding paragraphs. 24 The procedure consisted of 
condensation of the C0 2 (from a measured volume of 
sample air) in a coil immersed in liquid air or oxy¬ 
gen, evaporated into a closed titration vessel contain¬ 
ing excess standard alkali, absorption by the alkali, 
and back-titration with standard acid. 17 As it was 
set up the method was suitable for C0 2 concentra¬ 
tions from 350 rpm down to 10 ppm or below, and 
was limited only by the necessity for taking large air 
samples for low C0 2 concentrations. 24 

The apparatus used is shown schematically in Fig¬ 
ure 37. The essential part of the apparatus in the 


INLET SAMPLE 
LINE 


EXIT SAMPLE 
LINE 



WATER 

SATURATOR 


H 2 0 

•OUT 


CONDENSER 


h 2 o in 


—txy 


P = P RESSUR E GAUGES 
T = THE RMOGOUPLES 
^ELECTRIC HEATERS 


TO 

METER 


F LOWMETER 


Figure 37. Flow diagram for deposition of carbon dioxide by cooling. 
























































REMOVAL OF CO, BY MEANS OF SOLID ABSORBENTS 


221 


so-called equilibrium chamber is shown in Figure 38. 
This is constructed of heavy brass stock and contains 
an efficient filter composed of 6 layers of AA Fiber- 
glas. 

Experimental Procedure. After C0 2 -free air is 
admitted to the equilibrium chamber and the selected 
flow established, the cooling air stream is adjusted 
and retained to give constant readings on T 3 and T 6 . 
When T lt 7\>, and T 10 reach a steady temperature the 
high-pressure air is passed around the soda lime 
scrubber and a run is started with an exit sample. 
Consecutive samples at the same temperature are 
given consecutive run numbers. 



Control is directed to maintaining temperature 
equality in T u T 0 , and T 10 and to keeping these as 
close as possible to T 3 and T 6 . Actually, when steady 
conditions have been achieved all these temperatures 
are very close to each other. 7\, T 3 , and T 9 are 
measured on a potentiometer ( ± 2 microvolts), while 
all other temperatures are observed on a Celect-Ray 
indicating potentiometer, the accuracy of which is 
probably not better than —2 C. 


Results. Preliminary experiments at 200 psi and 
temperatures in the range —130 to —150C have 
been completed. These experiments had as their pur¬ 
pose a comparison of experimental results with the 
equilibrium concentrations calculated by means of 
various expressions involving empirical equations 
of state. It will be seen that the values calculated 
from the equations proposed are in good agreement 
with the experimental values. The results are plot¬ 
ted in Figures 39 and 40. The experimental points 
are connected by a straight line. To minimize sub¬ 
jective error, the experimental line was drawn first, 
after which the values derived from the equation were 
drawn in. 

It can be seen that the experimental values are 
slightly higher than the Groff-Gratch values, except 
for three points at lower temperatures. In Figure 39 
this difference amounts to about 0.3 to 0.8 C, the 
curves tending to be closer together at lower tempera¬ 
tures. This difference is inappreciable from a prac¬ 
tical standpoint but is considerable from the point of 
view of the usefulness of the data as a basis for theo¬ 
retical calculations. 

It is felt that, if the divergence of the Goff-Gratch 
and the experimental values is due to an error in 
equilibrium temperature measurement, the error lies 
not in inaccuracy of 7\ but in the measurement of 
the effective equilibrium temperature. It was hoped 
to eliminate this uncertainty by using a massive equi¬ 
librium chamber and low flows through it. Whether 
the divergence is real or erroneous cannot be decided 
with certainty. It appears that the only way to get 
high precision and to answer this question would be 
to use a stirred liquid cooling bath and careful thermo¬ 
static control. 

There is no doubt that the apparatus and proce¬ 
dure used are capable of considerable accuracy, how¬ 
ever, and experiments were under way to gather data 
at higher pressures at the termination of this con¬ 
tract. Preliminary results indicate that even the Goff- 
Gratch approximation is grossly in error at 600 psi. 
Further work is continuing under Navy Contract 
NObs-2477 with the University of Pennsylvania. 

Deposition of Solid Carbon Dioxide 

One method for the removal of C0 2 from the at¬ 
mosphere of a submarine (see Chapter 15) where a 
large supply of liquid oxygen is available, is to con¬ 
dense C0 2 as a solid by heat exchange. 18 The pre¬ 
cipitated carbon dioxide, either deposited on the tube 
wall or filtered from the cooled air, could he evapo- 


















































222 


AIR PURIFICATION 


rated and discharged to the ocean by means of a 
vacuum pump. 

A major uncertainty in the process lay in the type 
of deposit that might be obtained. No information 
was available to indicate whether the C0 2 would ad¬ 
here to the walls of the cooling surfaces, be carried 
through the tubes as particles in suspension in the 
air, or be partly deposited and partly entrained. It 
was recommended that the first experiment in the 
investigation of a liquid oxygen refrigeration process 
should be directed toward finding the answer to this 
question. 



Figure 39. Equilibrium concentration of C0 2 and C0 2 -air. 

Other projects of the section had to do with the 
mechanism of C0 2 removal from cold air by precipi¬ 
tation before air liquefaction (see Chapters 2 and 3), 
and it was felt necessary to know more about how, 
when, and where C0 2 is deposited from a refriger¬ 
ated air stream. 

Under all conditions tried thus far, precipitated 
CO- 2 adheres to the tube and apparently none of the 
solid leaves the tube as snow or particles in the exit 
air. A preliminary and qualitative approach to the 
second objective has been made, and some light has 


been shed on the probable mechanism of the C0 2 
deposition process but the investigation of the quanti¬ 
tative relationships has barely started. 

Because of the complete lack of knowledge of what 
might happen during the cooling of a stream of air 
and C0 2 , several variables were considered in the 
initial design of the experimental unit. It was ex¬ 
pected that the investigation would include study of 
the following variables: (1) concentration of C0 2 
in the inlet gas stream, (2) velocity of gas flow, (3) 
temperature drop across cooling surface, (4) cooling 
by cold wall vs direct cooling by mixing refrigerated 
air with C0 2 -rich air, (5) nature of surface; that is, 



Figure 40. Equilibrium of C0 2 -air. 


whether rough or polished, and possibly the compo¬ 
sition of the tube, (6) presence of baffles or other 
obstructions to flow, (7) shape of cross section of 
cooling surface, (8) use of centrifugal action, as in a 
cyclone filter, (9) density of gas, and (10) presence 
of crystals to act as nuclei for condensation. 

Experimental Unit.' 2 * The original unit constructed 
to investigate C0 2 deposition is shown in Figure 41. 
It was somewhat elaborate, and was so constructed 
that the C0 2 -air mixture could be directed either up 
or down through the tube; that either direct or in- 





REMOVAL OF CO., BY MEANS OF SOLID ABSORBENTS 


223 



Figure 41. Flow diagram of experimental unit for study of CO- removal from air by refrigeration. 


direct cooling could be used; and that any solid C0 2 
not adhering to the deposition tube could be filtered. 

The solid lines in Figure 41 represent the usual 
flow of the air and refrigeration fluids. The dotted 
lines represent alternate flow paths. For example, the 
normal path of the air-CO- mix is through the inner 
annulus of exchanger 1 down through the deposition 
tube, through the filter and then through the outer 
annulus of exchanger 1. By using the dashed lines, 
the direction of flow of the mix can he reversed so the 
gas flows upwards through the deposition tube. By 
passing dry air from exchanger 2 through coils im¬ 
mersed in liquid oxygen, a controlled flow of cold 
air can be injected directly into the C0 2 -air mix at 
either end of the deposition tube. Refrigeration is 
furnished by evaporating liquid oxygen. Dry air 
passes through the inner annulus of exchanger 2, 
bubbles through liquid oxygen in the refrigerated, 
and, with vaporized oxygen, flows through the outer 
shell of the deposition tube and through the outer 
annulus of exchanger 2. The several warm air lines 
shown in the figure are installed to provide means of 


warming the mix stream at critical points to vapor¬ 
ize CO- and determine the C0 2 deposition in various 
sections of the equipment. 

The deposition tube is shown in Figure 42. It con¬ 
sists of y 2 - in. OD x ^-in. ID copper tube, wrapped 
with a single layer of 100-mesh copper gauze and in¬ 
serted in a ID copper tube 5 ft long. The heat 

exchangers are Collins tubes (see Chapter 7), and the 
filter is a Porex filter tube, 2 in. in diameter and 6.5 
in. long, positioned in a case constructed of a copper 
tube and streamline fittings. 

Improved Unit. An improved unit 21 is shown in 
Figure 43. The essential difference between the 
units of Figures 41 and 43 are that the injection 
chambers, filter, warm air lines, and reverse flow 
lines were removed. An additional Collins tube was 
added to conserve refrigeration. Skin thermocouples 
throughout the unit were replaced by in-stream 
thermocouples. A heater was added at the exit of 
the deposition tube to vaporize any solid C0 2 that 
might issue from the deposition tube and thereby 
provide a homogeneous stream for accurate sampling. 























































































224 


AIR PURIFICATION 




i'oo-f'O 

GERMAN SILVER 


Figure 42. Carbon dioxide deposition tube. 


The C0 2 system was changed. In order to prevent 
the deposition of C0 2 in the cooling exchangers, the 
C0 2 is now added to the cold air stream immediately 
after exchanger 1. Since this air would be at the 
dew point of 3% C0 2 (the desired temperature for 
the entrant air-C0 2 mix to the deposition tube), the 
problem was presented of injecting the C0 2 without 
plugging the injection line or having deposition in 
the line before the deposition tube. Therefore, a 50% 
C0 2 -air mix is injected instead of pure C0 2 . The 
presence of the air lowers the dew point and also 
makes more difficult the deposition of C0 2 in the 
injection line. 

Even using the 50% C0 2 -air mixture, the point at 
which this was injected would undoubtedly plug 
gradually and produce a continual decrease in 
amount of C0 2 being injected. To overcome this 
difficulty the injector shown in Figure 42 was de¬ 
vised. The purpose was to have the injection point 
without thermal contact with the main streamline. 
The injected stream, at room temperature, would 
keep the German silver tube warm enough to remain 
above the dew point of the 50% injection stream. 
The injector has worked quite successfully and shows 
no tendency to plug. 

To overcome the effect of heat leak and also to 
obtain necessary adjustment of the temperature of 


the mixture entering at T-7, the line between ex¬ 
changer 1 and the deposition tube (about 3 ft long) 
was encased to provide an outer annulus through 
which cold air from V-3 (Figure 43), controlled in 
temperature with warm air from F-ll, could be 
passed. With this arrangement it has been possible 
to maintain T-4 and T-7 at the same temperature. 

The heat leak annulus would not be necessary if 
the C0 2 were injected immediately before the de¬ 
position tube. However, it is necessary to inject the 
C0 2 some distance before the tube in order to insure 
homogeneous mixing of the C0 2 and air before en¬ 
tering the deposition tube. 

Control of the temperature and flow rates in the 
revised apparatus has been satisfactory although it 
requires very delicate manipulation of valves. The 
main difficulties of control are caused by (1) the heat 
capacity of the apparatus, which causes temperature 
reactions resulting from changes of flow rates to be 
quite sluggish, and by (2) the necessary frequent 
replenishment of liquid refrigerant, which causes a 
fluctuation in the temperature level of the cooling 
stream to exchanger 1. 

Operation. To conduct a run, the unit is cooled to 
the desired operating temperature by means of liquid 
air in the refrigerator and by controlled flows of C0 2 - 
free air. When the temperatures throughout have 



























































REMOVAL OF CO, BY MEANS OF SOLID ABSORBENTS 


225 



Figure 43. Flow diagram of improved experimental unit for study of COa removal from air by refrigeration. 


Table 7. Tabulated calculated data. 



Heat 


Mix stream 


Cooling stream 


Deposited CO, 



Run 

leak 

Exit 

AT 

AH 

Flow 

AT 

AH 


7-7 

ho 

Q dep 

Diff 


Btu per hr 

cfh 

F 

Btu per hr 

cfh 

F 

Btu per hr 

lb per hr 

F 

F 

Btu per hr 

Btu per 

14 

56.6 

54.5 

19 

19.4 

230 

20 

86 

0.0672 

-165 

-185 

17.2 

7.2 

19 

43.7 

162 

18 

54.5 

224 

27 

113 

0.066 

-157 

-177 

16.8 

2.0 

20 

47.0 

161 

18 

54.0 

240 

27 

121 

0.1129 

-162 

-182 

28.9 

8.9 

21 

35.6 

162 

20 

60.5 

231 

28 

121 

0.1193 

-161 

-181 

30.6 

5.7 

24 

37.8 

161 

26 

78.4 

248 

36 

167 

0.2267 

-165 

-184 

58.1 

7.3 

26 

44.7 

161 

25 

75.2 

242 

37 

167.4 

0.2267 

-167 

-185 

58 

10.5 

27 

33.2 

162 

33 

100.0 

250 

42 

196.2 

0.2466 

-163 

-185 

63.4 

0.4 

28 

41.0 

162 

30 

90.7 

238 

44 

196 

0.238 

-172 

-185 

60.7 

-3.6 


reached steady conditions, the flow of 50% CCL-air 
mixture from the storage cylinders is started, and the 
inlet concentration adjusted to that desired for the 
run. During operation the concentrations of the inlet 
and outlet streams are measured hy an Orsat analysis. 
The pressure drop over the deposition tube is meas¬ 
ured by a mercury manometer and the pressure dif¬ 
ference recorded. 

As shown in Figure 43, a heater was installed after 
the deposition tube to vaporize any C0 2 that might 
blow through the deposition tube; a homogeneous 
stream would thereby be obtained, insuring an accu¬ 
rate sample of the effluent stream. Conduction along 
the tube wall from the heater to the deposition tube 


adversely affected conditions at the cold end of the 
tube, so the heater was not used during the runs 
presented in the report. 

As a run continues, the accumulation of C0 2 on 
the wall of the deposition tube causes a steady in¬ 
crease in pressure drop across the tube. The runs 
are terminated when the pressure drop reaches about 
100 in. of water. The time required to reach this 
pressure drop is about 45 to 60 min. 

Results. The data taken are summarized in Table 
7. From the observed data enthalpy and material 
balances were determined and the average rate of C0 2 
deposition calculated. 

In the enthalpy balances the heat leak was deter- 























































































MOLE PERCENTAGE OF CO 


226 


AIR PURIFICATION 



Figure 44. Saturation values of carbon dioxide in air. 



































REMOVAL OF CO., BY MEANS OF SOLID ABSORBENTS 


227 


mined for each run on the basis of data obtained 
(while C0 2 -free air was passing through the deposi¬ 
tion tube) immediately before starting the injection 
of COo. In calculations of enthalpy balances for 
operation with the C0 2 -air mix the heat leak was 
assumed to be unchanged from cooling of C0 2 -free 
air and allowance was made for the enthalpy of pre¬ 
cipitation of COo. 

Discussion of the Results. The most significant 
fact disclosed by the data is that C0 2 was retained 
by the tube, and apparently not entrained in the exit 
gas. It is not possible to state that there is no C0 2 
snow whatever in the leaving stream, because, with 
the present equipment, visual observation of the 
stream is not possible. The presence or absence of a 
small amount of solid C0 2 in the effluent is of aca¬ 
demic interest, however, as the analyses of this stream 
give the total C0 2 content, both vapor and solid phase, 
and the essential fact is that the C0 2 in the leaving 
stream is less than that in the entering stream. 

The most suggestive evidence on this point is ob¬ 
tained by comparing the exit C0 2 concentration with 
the dew point concentration under exit gas condi¬ 
tions. Figure 44 shows the saturation values of C0 2 
in its mixture with air, at various temperatures and 
pressures. From the data of Figure 44, the satura¬ 
tion curve of Figure 45 was determined. The actual 
measured concentrations of C0 2 in the effluent 
streams are also plotted in Figure 45. If there were 
appreciable quantities of solid C0 2 in the effluent, 
the total C0 2 concentration, gas and solid, would be 
above the dew point concentration corresponding to 
exit conditions. Actually, all experimental points 
fall below the saturation curve, although their dis¬ 
tance from the dew-point line is about equal to the 
experimental error. The analyses of C0 2 by means 
of the Orsat were probably accurate to 0.1 mole per 
cent. The temperature readings were taken from a 
Brown automatic potentiometer, and are probably 
correct to 1 F. Also, the thermocouple may read 
about 1 F too warm. The estimated errors are shown 
by the rectangles surrounding the data points of 
Figure 45. 

Further evidence was obtained that in the usual 
experiments no appreciable breakthrough occurred 
but in one run, breakthrough did occur and was meas¬ 
urable. Such breakthrough occurred in no other run. 
However, in making run 26, a false start was made 
when C0 2 depositing in the line before the deposition 
tube made it necessary to warm the unit to remove 
the C0 2 . As soon as there was no pressure drop 


across the tube, and apparently no C0 2 in the system, 
the run was restarted. It is quite likely that this 
procedure changed the surface characteristics of the 
deposition tube and resulted in the unusual break¬ 
through reported. 

Heat balances, including allowance for the heat 
of deposition of C0 2 , checked reasonably well, which 
also indicates that the C0 2 lost by the gas was 
actually retained as solid C0 2 by the tube. If solid 
C0 2 were precipitated and revaporized in the effluent 
after leaving the tube, enthalpy balances based on 
COo deposition would be in error. 

The data support the conclusion that C0 2 is solidi¬ 
fied and deposited on the tube wall in amounts rea¬ 
sonably close to those to be expected from the dew 
point concentration of the effluent stream. 

Because of C0 2 deposition on the wall of the tube, 
the pressure drop over the deposition tube steadily 
increased with time during each run. The pressure 
drop increases approximately exponentially with the 
weight of C0 2 deposited. 24 

Satisfactory quantitative calculations as to the 
mechanism and rate of deposition cannot be made 
from the data so far obtained. The thickness, density, 
and character of the deposit are unknown. Also, the 
tube wall temperature, which is a datum of funda¬ 
mental importance, is unknown and not readily cal¬ 
culable. The overall A^ for heat transfer is not accu¬ 
rately known because of the uncertainty in the tem¬ 
peratures of the cooling fluid. Again, the 100-mesh 
screen in the annular space prevents an accurate cal¬ 
culation of the annular side heat transfer coefficient. 

Process Requiring C0 2 Deposition. The results 
obtained in the experiments are favorable for the use 
of the direct cooling method for deposition of C0 2 , 
as far as size of equipment is concerned. The results 
of the calculations show that as much as 0.24 lb per 
hr of C0 2 can be deposited on a single copper tube 

-in. ID, Yi -in. OD and 5 ft long. To deposit 5 lb 
per hr of C0 2 (as would be necessary for a sub¬ 
marine) only 21 such tubes would be necessary. This 
number of tubes could be readily supported by a tube 
sheet 4 in. in diameter. No tube packing or special 
surface is required to insure the adhering of the C0 2 
to the surface. The above tube dimensions were 
chosen arbitrarily at the beginning of the experi¬ 
ments, and are not necessarily the optimum for the 
purpose. 

The practicability of the method will depend upon 

(1) the presence of liquid oxygen for refrigeration, 

(2) the space and weight requirement of auxiliary 




228 


AIR PURIFICATION 


equipment, and (3) the power requirement. The 
deposition unit itself seems to be practicable. The 
deposition unit would have to be constructed in dupli¬ 
cate to allow periodic vaporization C0 2 . The opti¬ 
mum time cycle would depend on a balance between 
power requirements and the disadvantages of short 
cycles. 


of these explosions; indeed, it can be said that no 
generalization on this point is possible, since local 
conditions probably play a decisive part in determin¬ 
ing the causes which give rise to them. 24 

The explosions generally occur in those parts of the 
system which contain liquid oxygen, usually in the 
reboiler itself, but in at least one case on record, an 


X 

5 


X 

UJ 

z 


w 

o 

o 


z 

UJ 

o 

£E 

UJ 

a 


uj 

_! 

O 

2 



EXIT MIX TEMPERATURE IN DEGREES P 


Figure 45. Exit C0 2 content vs temperature. 


9 4 7 The Removal of Combustible 
Contaminants from Air 

Danger and Causes of Explosions 

The occurrence of explosions in oxygen producing 
plants is well recognized in the industry and occa¬ 
sional reports of such incidents occur in the technical 
literature. Little can be said concerning the frequency 


explosion occurred in an entrainment separator 
through which passed vapor drawn from the reboiler. 
The violence of the explosions varies widely. Gen¬ 
erally, the only result is the destruction of the re¬ 
boiler and adjacent parts of the system without seri¬ 
ous damage to regions outside the cold box or to 
operating personnel. However, violent explosions 
causing considerable damage have occurred, and the 

















































REMOVAL OF CO, BY MEANS OF SOLID ABSORBENTS 


229 


danger of serious accidents must be considered al¬ 
ways to be present. 

There is not complete agreement as to the causes of 
explosions in oxygen plants. In general, however, 
it is accepted that the accumulation of solid acetylene 
in the presence of liquid oxygen is the important 
factor, although whether acetylene is initiary or con¬ 
tributory in its effect is not definitely certain. 

The presence of hydrocarbons other than acetylene 
has also been suggested as an important factor, al¬ 
though it is not supposed that such substances are 
responsible for initiating explosions, but only that 
they are detonated by some other substance, such 
as acetylene or acetylides. 

It has also been suggested that ozone may be re¬ 
sponsible for setting off the explosion, possibly acting 
to detonate other substances such as acetylene or 
even saturated hydrocarbons. If ozone is responsible, 
it may act in conjunction with unsaturated hydro¬ 
carbons, forming the highly unstable ozonides, long 
known to be subj ect to explosive decomposition; or 
it may undergo spontaneous explosive decomposi¬ 
tion, as it is prone to do when in the liquid state. 
Recent researches have shown that the ozone content 
of ordinary atmospheric air ranges around 0.02 ppm 
(depending greatly upon the locality and subject to 
wide fluctuations). The presence of ozone may be 
explained by the proximity of high tension wires 
and to the high static potential caused by friction of 
the driving belts of compressors as well as to the 
electrical charges arising from the passage of air 
through expansion valves; it is also produced in the 
atmosphere as the result of natural electrical phe¬ 
nomena. 

When liquid oxygen is produced, the danger of 
explosion is relatively small since periodic withdrawal 
of some of the reboiler contents would prevent the 
accumulation of acetylene (and other hydrocarbons), 
unless these substances tend to precipitate as a film 
on the inner surfaces of the reboiler and thus not be 
removable as a suspension in the withdrawn liquid. 

In a unit which produces gaseous oxygen the ac¬ 
cumulation of acetylene and other hydrocarbons in 
the reboiler can proceed to an extent depending upon 
the intervals between which the equipment is warmed 
up for repairs, cleaning, etc. It is in this type of unit 
that the hazards are greatest, and most of the re¬ 
corded examples of explosions which have occurred 
have been in gas-producing units. 

No systematic methods of combating these hazards 
are in use in the oxygen industry. Certain precautions 


are frequently taken to prevent an explosion from 
causing injury to workmen or the extensive destruc¬ 
tion of adjacent equipment. It is the custom in the 
industry to locate those pieces of apparatus liable to 
explosion in concrete pits or in exterior vessels fitted 
with blowout heads, and to drain the reboiler at fre¬ 
quent intervals. 

Acetylene 

The presence of acetylene and other hydrocarbons 
in air is probably caused entirely by such industrial 
operations involving the use and combustion of hydro¬ 
carbons, as the use of acetylene for welding, the 
operation of internal combustion engines, the use of 
oil for heat or power generation, etc. 

Small amounts of hydrocarbon contaminants could 
conceivably be produced in the cylinders of oil-lubri¬ 
cated compressors, but there is no evidence that the 
temperatures attained in a compressor cylinder are 
high enough to cause any appreciable cracking of the 
lubricant. 27 It has been estimated, assuming a C 8 
hydrocarbon, that if a temperature of 500 C were 
maintained in a cylinder for a long enough time to 
establish equilibrium in the reaction 

CsH 18 C 6 H 14 + C 2 H 2 + H 2 , 

a maxirpum of 0.3 ppm of acetylene would be formed, 
certainly an extreme upper limit not reached in prac¬ 
tice. 

The concentration of acetylene in air has been 
measured 26 and found to range between 0.01 to 0.1 
ppm rising to as much as 2 to 3 ppm in the immediate 
vicinity of acetylene generating plants. 

No information is available concerning the nature 
and concentration of other hydrocarbons in air. It 
is probable that in highly industrialized areas con¬ 
siderable amounts of low-molecular-weight hydro¬ 
carbons are present in the atmosphere. Liquid oxy¬ 
gen units operating in an industrialized section of 
Cambridge, Massachusetts, produce a liquid oxygen 
which is usually milky with suspended flocks of a 
suspended material which on examination has been 
shown to be of a hydrocarbon nature (but of un¬ 
known composition). 

Analysis for acetylene in the reboiler of an M-7 
type unit at the time when the liquid has just formed 
an insufficient quantity to fill the reboiler showed 0.2 
ppm C 2 H 2 present. It has been shown that if the 
entering air contains more than 0.04 ppm of acety¬ 
lene, the latter can accumulate in the reboiler. 22 It is 
probable that hydrocarbons such as ethane, ethylene 



230 


AIR PURIFICATION 


and heavier hydrocarbons will accumulate at concen¬ 
trations of the same order of magnitude, and the 
same is true of ozone (bp—122 C) and nitrogen 
dioxide. Studies have been made as to the best 
methods for the removal of hydrocarbons and consid¬ 
erable work has been done on the removal of acetylene 
by adsorption on active charcoal, and by its catalytic 
oxidation to CO_. and H 2 0. 

Catalytic Oxidation of Acetylene 22 ’ 24 

The compressors in use to supply air for air lique¬ 
fying plants can be divided into two classes. 

1. High pressure (3,000 psi). 

a. Oil-lubricated pistons. 

b. Dry pistons. 

2. Low pressure (100 to 150 psi). 

a. Oil-lubricated pistons. 

b. Dry pistons. 

The high-pressure compressors are usually four- 
stage compressors with the stage discharge pressures 
at 55 psi, 175 psi, 750 psi, and 3,000 psi respectively, 
with intercooling between each stage. The low- 
pressure compressors are usually tw T o-stage com¬ 
pressors with intercooling between stages. The dis¬ 
charge conditions for the second compressor stage 
may vary from 348 to 359 F (176 to 182 C) for a 
discharge pressure of 107 psia. 

It would seem possible therefore to operate a cata¬ 
lyst at about 100 psia and 300 to 350 F (149 to 
172 C). There would be a choice of conditions in the 
high pressure compressor; that is, operation of cata¬ 
lyst at 55, or 175, or 750 psi. 

The possibility of condensation of water on the 
catalyst during operation can probably be ruled out 
for any possible application. 22 

The pressure of oil in the air delivered by the com¬ 
pressor would of course depend upon whether the 
pistons were oil-lubricated or dry. The actual amount 
of oil carried through with the air would in any case 
depend upon the condition of the individual com¬ 
pressor, that is, type of oil, condition of rings, etc. 
The temperature of the oil delivered with the air 
would also depend to a great extent upon the indi¬ 
vidual compressor. 

Catalysts of Interest Reported in the Literature. 
Much of the material of interest refers to the oxida¬ 
tion of carbon monoxide rather than acetylene. Many 
CO oxidation catalysts are also C 2 H 2 oxidation cata¬ 
lysts, and the same promoters are often effective in 
both cases. 


Interest in the problem of CO oxidation during 
World War I centered, at first, largely around chemi¬ 
cal oxidants. Of the many oxidants tried it was found 
that a 1/1 mixture of MnO s and Ag 2 0 acted eata- 
lytically, not as a stoichiometric oxidant. This finding 
shifted the line of attack, which was thereafter di¬ 
rected at metal-oxide catalysts. In the course of the 
work on active preparation of Co 2 0 3 -f- Mn0 2 
-)- Ag 2 0 this mixture was found to he easily poisoned 
by HoO; in fact, this sensitivity toward H 2 0 seemed 
to run parallel to the CO-oxidizing ability of the 
catalysts. The first agent actually made on a large 
scale for use in protective masks was 50% Mn0 2 
-f- 30% CuO+ 15% Co 2 O s + 5% Ag,0, called 
Hopcalite I. Due to lack of time for basic tests, the 
familiar 60% MnOo + 40% CuO Hopcalite, which 
had already been prepared, was not tried in the field 
until later. 

Further work has been done in NDRC, Division 
10 on the oxidation of CO with Hopcalite and other 
agents. 13 ’ 24 Improvements were made in the meth¬ 
ods of preparing Mn0 2 , so that gel-type Hopcalites 
could be produced which, in some cases, were supe¬ 
rior to commercial MSA Hopcalite. a The addition of 
Ag 2 0 to Mn0 2 had little effect, but a combination of 
Ag 2 0 + Mn0 2 -|- PdO was very active. Among 
the various Hopcalites, the ratio Mn/Cu often had 
less to do with the final activity than incidental varia¬ 
tions in the preparative methods. 

Promoters. In many of the catalyst preparations 
cited promoters were involved, though they were not 
sought for as such. Pd has been used as a promoter 
in a Cu catalyst for oxidizing a mixture of H 2 + CO 
+ 0 2 . In a thoria catalyst for oxidation of CO, 
Ce0 2 exerted optimum promoter action at a concen¬ 
tration of 0.96% which is also the best composition 
for ceriathoria gas mantles. 

During World War I, while Hopcalite was being 
developed in the United States, British researchers 
were working on mixtures of CuO and MnO a , with 
1 to 5% Ce0 2 as promoter for the oxidation of CO. 
Such mixtures as CuO + MnO a , AgoO -j- Mn0 2 , 
CuO + Fe 2 0 3 , and the higher oxides of Ni, Co, or 
Fe with Mn0 2 were found more active than the 
single oxides. Such catalysts were further improved 
by promoters, such as Ce0 2 , Pd, or Ag. The follow¬ 
ing quotation is especially significant in connection 
with the silver-Hopcalite catalysts used in our acety¬ 
lene investigations. 

11 Product of the Mine Safety Appliance Co., Pittsburgh, 
Pa. 





REMOVAL OF CO.. BY MEANS OF SOLID ABSORBENTS 


231 


“Taking the CuO -f- Mn0 2 mixture, and adding 
as a third constituent either ceria, cobalitic oxide, 
reduced metallic palladium, or silver oxide, the activ¬ 
ity became much too great to compare with the pre¬ 
vious results, by the method indicated.” 

Catalysts for Oxidation of Acetylene. Most of the 
catalysts for the oxidation of C 2 H 2 listed in the litera¬ 
ture were chosen specifically because they formed 
useful intermediate oxidation products, such as ace¬ 
tone, and acetaldehyde. Thus, the oxidations were 
incomplete and the concentrations of C 2 H 2 used were 
exceedingly high compared with those of interest in 
the present study. 

Russian investigations 22 were directed toward the 
oxidation of small quantities of acetylene, with the 
stated purpose (in some of the papers) of preventing 
explosions due to accumulation of C 2 H 2 in the liquid 
oxygen of air-fractionating plants. 

Present Experimental Investigation 

The apparatus used, shown schematically in Fig¬ 
ure 46, was constructed for the study of the removal 
of traces (1 to 10 ppm) of hydrocarbons (particu¬ 
larly acetylene) from air at 100 psi by means of cata¬ 
lytic oxidation. 

Catalysts. The catalysts 24 used in the work can be 
divided into the following categories: 

1. MSA Hopcalite. 

2. MSA Hopcalite impregnated with Ag oxide and 
other Ag salts. 


3. Mn0 2 catalysts with and without additives such 
as CuO and Ag 2 0, prepared here. 

4. Gel Hopcalite furnished by R. N. Pease. 25 

5. Inert supports (silica gel and plaster of Paris) 
impregnated with Mn and other oxides. 

6. Other catalysts. 

Gases Used. All the catalytic runs made to date 
have been with air-acetylene mixtures containing 5 
to 7 ppm of acetylene. The analytical method for 
acetylene is fully described 22 and the groundwork has 
been laid for work with other hydrocarbons. 

As a typical light saturated hydrocarbon, butane 
was selected for the development of an analytical 
method to be used in connection with studies of the 
catalytic oxidation of substances other than acetylene. 
Concentrations of the order of a few parts per mil¬ 
lion are obviously beyond the range of standard gas- 
analysis equipment. The possibility of using a macro¬ 
method after condensation of the hydrocarbon in coils 
immersed in liquid 0 2 or air using a Bureau of Mines- 
type Or sat apparatus was employed in the standard¬ 
ization of a butane mixture made up in a bomb. It 
was found that smaller gas samples could be taken 
if, instead of using the standard gas analysis ap¬ 
paratus, the condensed butane was burned and the 
C0 2 formed titrated by the special method reported 
previously. 17 ’ 24 The latter procedure was chosen for 
future application. 

Conditions. All the experimental work on the cata¬ 
lysts was carried on at 100 psi with a flow rate of 50 


LEGEND 

A-LIQUID OXYGEN STORAGE 
B-COOLING JACKET 
C-EQUILBRIUM CHAMBER 
Q-PRESSURE GAGES 


D-PRECOOLER 
E-SOOA LIME BOMB 
F-CALCIUM CHLORI0E 
DRYING BOMB 



Figure 46. Apparatus for the removal of hydrocarbons from air by catalytic oxidation. 














































232 


AIR PURIFICATION 




Table 8. Conditions: 200 F, 100 psi, 50 scfh, 25 cc, 16- 

to 20-mesh catalyst. 



Run 

No. 

Catalyst No. 
X-l-CO 

Description of catalyst 

ppm 

inlet 

c.h, 

exit 

% 

Removal 

13 

5 

Group 1 

Mn0 2 -Ag 2 0 6:4 (CEL) 

5.2 

0 

100 

14 

8 

Mn0 2 -Ag 2 0 6:1 (CEL) 

5.3 

0 

100 

16 

3 

MnCh-AgaO-PdO (Pease) 

4.7 

0 

100 

18 

6 

Mn0 2 -Ag 2 0 6:2 (CEL) 

6.1 

0 

100 

20 

13 

Mn0 2 -Ag 2 0 gel 6 :4 (CEL) 

5.1 

0 

100 

21 

2 

Mn0 2 -Ag 2 0-Cu0 gel (Pease) 

4.2 

0 

100 

23 

14 

Mn0 2 -Ag 2 0 gel 6:4 (CEL) 

4.3 

0 

100 

25 

16 

MSA Hopcalite-Ag 2 0 (100:5) (CEL) 

4.3 

0 

100 

26 

17 

MSA Hopcalite-Ag 2 0 (74:7.4) (CEL) 

4.7 

0 

100 

32 

22 

Ag 2 0 on silica gel (CEL) 

4.6 

0 

100 

37 

29 

Ag 2 0 on silica gel (CEL) 

5.1 

0 

100 

51 

39 

MSA Hopcalite -f- Ag-0 on P. of P.* (10:1) (CEL) 

5.6 

0 

100 

52 

41 

MSA Hopcalite + Ag 2 0 on P. of P. (10 :2) (CEL) 

6.4 

0 

100 

54 

46 

X-l-CO 39 activated at 250 C, 3 hr 

6.4 

0 

100 

55 

51 

X-l-CO 41 activated at 270 C. 3 hr 

5.7 

0 

100 

57 

58 

X-l-CO 7 activated at 250 C, 3 hr 

5.7 

0 

100 

60 

67 

X-l-CO 56 (Mn0 2 -Ag 2 0 on active C) activated at 250 C 

7.1 

0 

100 

58 

65 

Group 2 

X-l-CO 50 (Hopcalite-Ag 2 0-P. of P.) activated at 260 C 

5.7 

0.3 

95 

53 

44 

X-l-CO 3 activated at 250 C, 3.5 hr 

6.4 

1.2 

81 

59 

66 

X-l-CO 53 (SiO>, Ag 2 0, P. of P. activated at 250 C) 

5.8 

1.1 

81 

34 

24 

KMnCh-AgMnOi on silica gel (CEL) 

5.4 

0.6 

89 

12 

7 

MSA Hopcalite impregnated with Ag 2 0 (CEL) 

5.4 

0.9 

84 

22 

15 

Mn0 2 -Ag 2 0 gel 6:2 (CEL) 

4.0 

0.8 

80 

24 

15 

Mn0 2 -Ag 2 0 gel 6:2 (CEL) 

4.6 

0.3 

94 

39 

30 

Mn0 2 -Ag 2 0 on P. of P. (CEL) 

6.0 

1.2 

80 

44 

34 

X-l-CO 30 activated at 210 C, 3 hr 

5.9 

1.7 

71 

40 

31 

MSA Hopcalite activated at 200 C, 1.5 hr 

5.7 

2.0 

65 

15 

1 

Mn0 2 -Cu0 2:l (Pease) 

5.3 

2.2 

59 

11 

12A 

MSA Hopcalite as received 

4.9 

2.3 

53 

19 

11 

Mn0 2 -CuO 6 :4 (CEL) 

6.1 

3.1 

49 

49 

43 

X-l-CO 10 activated at 250 C, 3 hr 

5.6 

2.6 

54 

50 

42 

X-l-CO 11 activated at 250 C, 3 hr 

5.6 

3.2 

44 

33 

23 

Group 3 

CuO-Ag 2 0 on silica gel (CEL) 

4.8 

3.3 

31 

17 

10 

Mn0 2 -CuO gel 6:4 (CEL) 

4.7 

3.6 

23 

43 

27 

KMnOi-AgMnOi on P. of P. (CEL) 

4.8 

4.0 

20 

36 

26 

Ag 2 0 on P. of P. (ppt’d in situ) (CEL) 

4.7 

3.8 

19 

29 

4 

Davso Platinized silica gel 

4.6 

3.9 

15 

27 

18 

MSA Hopcalite-CuO-HsPCL 

5.2 

4.7 

9 

28 

19 

Baker Tech. (85%) MnO a 

5.2 

4.8 

8 

8 

12B 

MSA Hopcalite wetted, dried at 110 C 

5.3 

4.7 

11 

30 

20 

Group 4 

Silica gel 

4.6 

4.6 

0 

31 

21 

Cr 2 0 2 (9%) on silica gel (CEL) 

4.8 

4.8 

0 

41 

35 

CWSN 249 AY carbon 

5.9 

5.9 

0 

42 

36 

Salcomine 

5.4 

5.4 

0 

36 

25 

Mn0 2 -Ag 2 0 on silica gel (CEL) 

4.7 

4.7 

0 


Note. Exit analyses are averages of two simultaneous, parallel samples. Inlet analyses are generally averages of several single samples. With few 
exceptions, averages of analyses of same sample generally check individual results within ±0.2 ppm. 

* P. of P. = Plaster of Paris. 


scfh and a catalyst volume of 25 ml. This is equiva¬ 
lent to a space velocity of 50,000 hr -1 (all space veloci¬ 
ties reported herein are referred to standard condi¬ 
tions; that is, sv = scfh per cf catalyst volume). The 
air-acetylene mixtures were made up in Harrisburg 


bombs and pressured up to 3,000 psi. The C 2 Ho con¬ 
centration was 5 to 7 ppm. Experimental runs were 
carried out under three different sets of conditions: 
dry mixture, water saturated mixtures, and water- 
and oil-saturated mixtures. 











REMOVAL OF CO., BY MEANS OF SOLID ABSORBENTS 


233 


The dry runs were made at a catalyst temperature 
of 200 F. This was chosen because the catalyst which 
was chosen as a standard, MSA Hopcalite, gave 53% 
removal under these conditions and therefore would 
serve as a good basis for comparison. 


graded Hopcalite-Ag 2 0 catalysts was also run to 
determine the minimum silver oxide necessary for 
complete acetylene removal under these conditions. 
The results of these runs are given in Table 9. 

Two runs were made at a catalyst temperature of 


Table 9 


Conditions: 300 F, 100 psi, 50 scfh, 25 cc, 16- to 20-mesh catalyst, water-saturator at 150 F. 


Run 

No. 

Catalyst No. 
X-l-CO 

Description of catalyst 

ppm 

inlet 

C 2 H 2 

exit 

% 

Removal 

61 

5 

MnCh-AgaO 6:4 (CEL) 

6.3 

0 

100 

66 

6 

Mn0 2 -Ag 2 0 6 :2 (CEL) 

5.5 

0 

100 

67 

13 

MnCb-AgaO gel 6 :4 (CEL) 

5.5 

0 

100 

64 



6.2 

0.3 

95 


29 

Ag 2 0 on silica gel (CEL) 




65 



6.2 

0 

100 

75 

39 

MSA Hopcalite + Ag 2 0 on P. of P. (10 :1) 

5.6 

0 

100 

72 

72 

MSA Hopcalite 5% Ag 2 0 (CEL) 

5.8 

0 

100 

73 

73 

MSA Hopcalite + 10.0% Ag 2 0 (CEL) 

5.6 

0 

100 

68 

16 

MSA Hopcalite + AgMnCh (100 :5) (CEL) 

5.5 

2 

96 

62 

8 

Mn0 2 -Ag 2 0 6 :1 (CEL) 

6.2 

3 

95 

63 

12A 

MSA Hopcalite 

6.2 

2.1 

66 

69 

69 

MSA Hopcalite + 0.1% Ag 2 0 (CEL) 

5.8 

1.6 

72 

70 

70 

MSA Hopcalite + 0.5% Ag 2 0 (CEL) 

5.8 

1.9 

67 

71 

71 

MSA Hopcalite + 1.0% Ag 2 0 (CEL) 

5.8 

0.8 

86 

74 

69 

X-l-CO 69; Act. 3.5 hr 250 C 

5.6 

1.2 

79 


The water-saturated runs were made at a catalyst 
temperature of 300 F and a water saturator tempera¬ 
ture of 150 F. 

The water- and oil-saturated runs were made at a 
water-saturator temperature of 150 F and at oil- 
saturator temperatures of 150 F, 225 F, 275 F, and 
300 F. 

Experimental Results. The first 60 runs were made 
at 200 F, 100 psi, using dry (that is, saturated at 
2,500 psi) mixtures of air-acetylene (6 to 7 ppm). 

The results of these runs are given in Table 8. 
They are grouped in four classes: (1) runs in which 
no acetylene was detectable in the exit gas; (2) runs 
in which removal was less than 100% but better than 
50% ; (3) runs in which some removal was observed; 
and (4) those in which no removal was effected. 24 

It will be seen that the first group includes, with¬ 
out exception, only catalysts containing silver oxide. 
Without exception, catalysts which do not contain 
silver remove less than 65% and catalysts which are 
not Hopcalite or Hopcalites plus Ag 2 0 are quite in¬ 
effective. 

The water-saturated runs were made with a cata¬ 
lyst temperature of 300 F, a water-saturator tempera¬ 
ture of 150 F, at 100 psi and using air-acetylene mix¬ 
tures of 5 to 7 ppm concentration and MSA Hop¬ 
calite was run as a basis for comparison. A series of 


200 F further to separate the 5% and 10% Ag 2 0 on 
Hopcalite. These data are given in Table 10. 


Table 10. Conditions: catalyst temperature 200 F, 100 
psi, 50 scfh, water-saturator temperature 150 F. 


Run 

No. 

Cata¬ 

lyst 

No. 

X-l-CO 

Description of catalyst 

ppm 

inlet 

CJL 

exit 

% 

Re¬ 

moval 

78 

12A 

MSA Hopcalite 

5.3 

5.3 

0 

76 

72 

MSA Hopcalite + 5% Ag 2 0 

5.6 

0.8 

86 

77 

73 

MSA Hopcalite + 10% Ag 2 0 

5.6 

0 

100 


From these data, it would seem that a 10% Ag 2 0 
on MSA Hopcalite would be a likely choice for fur¬ 
ther work with water- and oil-saturated air-acetylene 
mixtures. 

A series of runs was next made with water and oil 
saturation, with oil-saturator temperatures of 300, 
275, 220, and 150 F. The results are given in Table 
11 . 

The difference between catalyst No. X-l-CO-73 
and X-1-CO-73-B was only in the method of grind¬ 
ing before pelleting and mashing. X-l-CO-73 was 
ground in a mortar and pestle wet, whereas X-l-CO- 
73-B was ground dry in a ball mill. 

In an effort to determine the effectiveness of the 
Hopcalite-Ag 2 0 (10%) catalyst in burning the oil 
coming from the oil saturator, the amount of vola- 













234 


AIR PURIFICATION 


tilized and the amount burned were determined on 
separate runs in three temperature regions. 

The volatilized oil was condensed in a coil similar 
to that used in the acetylene analysis method except 
for the addition of an AA Fiberglas filter. This coil, 
which was located in place of the usual catalyst bomb, 
was cooled with liquid oxygen. At the end of each 
run, the condensed oil was removed from the coil 
with acetone and carbon tetrachloride. The solvents 
were evaporated and the oil weighed. 

For analysis of oil burned, it was decided to deter¬ 
mine C0 2 in exit samples from the unit during regu¬ 
lar C ; H 2 runs, using the procedure of condensing the 


These would be included in the burned-oil but ex¬ 
cluded from the volatilized-oil measurements, thus 
appreciably affecting the results at low oil levels. 

Conclusions. From the experimental data it is ap¬ 
parent that it is possible to remove acetylene (ca 
5 to 7 ppm) from an air-acetylene mixture at condi¬ 
tions approximating those to be found on the dis¬ 
charge side of a low-pressure (100 psi) compressor 
or after the first or second stage of a high-pressure 
(3,000 psi) compressor. It has been shown experi¬ 
mentally by others that the efficiency of Mn0 2 and 
of CuO increased with decreasing concentrations of 
acetylene. Inasmuch as acetylene concentrations 


Table 11 


Conditions: catalyst temperature 300 F, 100 psi, 50 scfh, 25 cc, 16- to 20-mesh catalyst, water-saturator tempera¬ 
ture 150 F, oil-saturator temperature as indicated. 


Run 

No. 

Catalyst 

No. 

X-l-CO 

Oil-satu¬ 
rator tem¬ 
perature 

Description of catalyst 

ppm 

inlet 

C 2 H 2 

exit 

% 

Removal 

79 

12-A 

300 F 

MSA Hopcalite 

6.5 

6.5 

0 

80 

73 

300 F 

MSA Hopcalite + 10% Ag 2 0 (CEL) 

6.1 

1.9 

70 

86 

73-B 

300 F 

MSA Hopcalite + 10% Ag 2 0 powdered in ball 







mill before pelleting (CEL) 

6.0 

0.4 

93 

87 

73-B 

225 F 

MSA Hopcalite + 10% Ag 2 0 powdered in ball 







mill before pelleting (CEL) 

5.3 

0 

100 

81 

73 

220 F 

MSA Hopcalite + 10% Ag 2 0 (CEL) 

6.1 

0 

100 

83 

39 

220 F 

MSA Hopcalite Ag 2 0 (6:4:1) (CEL) 

5.3 

0 

100 

84 

22 

220 F 

Ag 2 0 on Silica gel (CEL) 

5.9 

0 

100 

82 

73 

150 F 

MSA Hopcalite + 10% Ag 2 0 (CEL) 

4.7 

0 

100 


C0 2 in coils and allowing it to expand into the titra¬ 
tion vessel. These analyses were subject to two 
sources of contaminant C0 2 : the content of the inlet 
air, and the C0 2 resulting from the oxidation of 
C 2 H 2 on the catalyst. Correction was made for the 
former by C0 2 analysis of the inlet air (from which 
the C0 2 was largely removed by the insertion of a 
soda-lime scrubber on the high-pressure side), and 
for the latter by converting the inlet C 2 H 2 analyses 
to ppm C0 2 (in these runs the oxidation was 100%). 
The corrected C0 2 values were then converted to 
grams of oil per standard megaliter of air, consider¬ 
ing the oil to be composed of 85% carbon. The re¬ 
sults are given in Table 12 and Figure 47. 

At an oil-saturator temperature of 275 F, about 
60% of the oil was burned, at 220 F about 83%, and 
at 150 F over 100%. This last result was probably 
due to the error in extracting and weighing a quan¬ 
tity of oil in the range of 70 mg, as well as to the 
observed phenomenon that the heated oil released 
hydrocarbons which were gaseous at room tempera¬ 
ture but condensable at the temperature of liquid 0 2 . 


Table 12 


Oil tem- Oil Oil tem- Oil 

perature volatilized perature burned 

275 F 162 

168 g per 10° liters 275 F 97.3 g per 10 s liters 
220 F 50.0 g per 10° liters 221 F 41.3 g per 10 a liters 



SATURATOR TEMPERATURE F 

Figure 47. Amount of oil vaporized and burned in re¬ 
lation to the oil saturation temperature. 










REMOVAL OF CO, BY MEANS OF SOLID ABSORBENTS 


235 


under actual operating conditions average 0.01 to 
0.1 ppm (and may go as high as 2 to 3 ppm under 
extreme conditions), it is not unreasonable to as¬ 
sume that the Hopcalite -(-10% AgoO catalyst will 
be more efficient with lower concentrations of acety¬ 
lene than we have shown with 5 to 7 ppm. 

From the data it would seem that 10% Ag 2 0 on 
Hopcalite would be enough silver as a promoter to 
do a good job. However, actual life tests would be 
necessary to support this assumption. 

It has also been shown that from 60 to 100% of 
the oil in the air stream (depending upon the tem¬ 
perature of the oil saturator) is burned on the cata¬ 
lyst together with the acetylene. 24 

The following projects were unfinished at termina¬ 


tion of the NDRC contracts. Further information 
may be obtained under Navy contract Nobs 4777. 

1. The life of the catalyst using dry air-acetylene 
mixtures. 

2. The life of the catalyst using water saturated 
air-acetylene mixtures. 

3. The life of the catalyst using water and oil satu¬ 
rated air-acetylene mixtures. 

4. The removal of hydrocarbons other than acety¬ 
lene for example, propane and butane. 

5. Methods of reactivating a catalyst grown in¬ 
active in use. 

6. Addition of promoters other than silver, for 
example, Ce0 2 . 



Chapter 10 

MISCELLANEOUS EQUIPMENT 


By J. H. Rushton 


101 INSULATION 

T he efficiency of liquid air fractionation plants 
is strongly dependent on the effectiveness of 
the thermal insulation enclosing the low-temperature 
portions of the plant. For the mobile and air-trans¬ 
portable plants it is desirable to use an insulating 
material that is both highly effective and light in 
weight. An evaluation of various materials could 
not be made on the basis of available information, and 
therefore some experimental tests were required. 

Tests were made 2 on thirteen different materials 
at one or more densities in the range of 2 to 14 lb 
per cu ft. Results are given in Table 1. All tests were 
made under similar conditions in the same apparatus. 
The criterion of insulation quality was the total heat 
transfer through the insulation. 

The apparatus used consisted of a tube 6 ft high 
by 4 in. OD, supported in a rectangular box 7 ft high 
by 20 in. square. The insulation to be tested was 
packed around the tube, filling the free volume of the 
box. The tube was filled with liquid air and the heat 
flow through the insulation was measured indirectly 
by the rate of evaporation of the liquid air after the 
apparatus had been cooled to equilibrium tempera¬ 
tures. 

Characteristics of the three outstanding insulations 
are given in Table 2. Fiberglas shoddy from mixed 
yarns and scrap from forming, twisting and plying 
operations, proved to be the best insulation material 
for use in mobile oxygen units. Santocel insulation 
was superior to this Fiberglas in that it had a lower 
heat transfer, but the Santocel powder is undesirable 
since it can be lost from a unit by being blown from 
the cold box as a result of a break in the high-pressure 
apparatus. It is possible that packing the Fiberglas 
to about 8 lb per cu ft might make it as effective as 
Santocel at its normal density of 7.4 lb per cu ft. 

Dry Zero kapok insulation was the lightest of the 
effective insulations, but its effectiveness was proba¬ 
bly due to its manner of installation. Paper backing 
on the material was used to form vertical and hori¬ 
zontal convection current barriers. This method of 
application would be impractical in oxygen units. No 
test on this material in bulk form was made. 


An optimum density was not found for any insula¬ 
tion in these tests. In all cases the insulating effec¬ 
tiveness improved with increasing density up to the 
highest densities used. Other similar tests 3 on various 
types of glass wool showed optimum densities rang¬ 
ing from 5 to 8 lb per cu ft, but the insulation thick¬ 
ness used was only about 4 in., compared to the 8-in. 
thickness used in the more comprehensive tests. The 
optimum density for any insulation is probably a 
function of insulation thickness, temperature differ¬ 
ence, and size, shape, and orientation of the insulated 
system. 

For low-cost insulation when weight is not of im¬ 
portance, rock wool should prove most suitable since 
this is almost as effective as the more expensive 
materials. 

102 FILTERS 

The use of special filters has been required in some 
XDRC oxygen plants for (1) the removal of fine oil 
particles from the compressed air fed to the separa¬ 
tion system, and (2) the removal of solid carbon 
dioxide particles from liquid air streams. 

The complete removal of oil from the compressed- 
air feed was first found necessary in the low-pressure 
M-7 unit. The small amount of oil passing through 
conventional air separators seriously fouled the re¬ 
versing exchangers within several days of operation. 
The use of gas-mask asbestos paper 4 proved quite 
successful in removing the extremely fine oil particles 
that could not be removed by conventional means. 
In the design of filters using this paper, air velocities 
of 10 ft per min or less are used, with 8 to 12 layers 
of paper. The paper is usually wound on long tubes 
with the gas flow being radial inward, and a sufficient 
number of tubes in parallel is used to obtain the 
necessary filtering area. The oil particles are retained 
in the porous paper, and the paper must he replaced 
periodically. The life of the paper obviously depends 
on the amount of oil passing the preliminary sepa¬ 
rators and filters used. 

Fiberglas AA mat, phenol-formaldehyde treated, 
has proved about as effective as the asbestos paper. 


236 


FILTERS 


237 


Table 1. Summary of results 

Insulation 

Density 
lb per cu 
ft 

Per cent|| 
moisture 

Heat leakf 
(0% evap.) 

Btu per hr 

A7W 

F 

F 

F 

Run No. 

1. Rock wool* 

11.6] 







1-B 

(white) 

11.6 

- 

0.0 

300 




1-C 


12.2 J 







1-D 

2. Fiberglas 

2.0] 



940 





T.W.F. 

3.4 


0 1 

780 

4 

1 

37 

2-A 


6.1 

► 


430 

5 

2 

21 

2-C 


8.3 



320 

3 

2 

12 

2-D 

3. Fiberglas 

4.4] 

1 

n n 

440 

2 

0 

26 

3-A 

bulk silk “E” 

5.7 J 

r 

u. u 

290 

4 

3 

14 

3-B 

4. Fiberglas 

4.2] 



1,220 

4 

19 

28 

4-A 

semi-rigid batts 

5.7 


0.1 

450 

3 

2 


4-B 


5.7, 



450 

2 

3 

30 

4-C 

5. Fiberglas 

2.9' 



750 

1 

1 

42 

5-A 

continuous shoddy 

5.3 


0 4 

480 

3 

0 

26 

5-B 


7.4 



350 

3 

1 

15 

5-C 


8.8 



350 

3 

1 

14 

5-D 

6. Santocel 

7.3 


3.1 

174 

0 

0 

0 

6-A 

7. Eagle Picher 7-B 

9.7 


0.0 

325 

2 

2 

7 

7-A 

granulated wool 









8. Fiberglas 

5.5 


5.4 

570 

0 

2 

27 

8-A 

garnetted shoddy 









9. Fiberglas heat 

4.54 


0.1 

405 

1 

1 

19 

9-A 

cleaned bulk cotton 









10. Jolms-Manville 

9.1' 



375 

3 

3 

11 

10-A 

rock wool 

13.3 

[ 

0.9 

345 

2 

1 

6 

10-B 

11. Ferrotherm 

14.1 

I 


570 

2 

4 

10 

11-A 

12. Dry Zero 

1.9' 

i 

16 1 

310 

2 

3 

16 

12-A 

13. Fiberglas shoddy§ 

5.8 

r 


270 




13-A 


* The score of this material is not known and hence it cannot be definitely identified, 
t Extrapolated value. 

J AT’ s—Subscript denotes elevation. Values given are average values of AT between surface temperature and air temperature at center 
and edges of box. 

§ Fiberglas shoddy from mixed yarns and from forming, twisting and plying operations. 

|| This moisture content is merely an indication of how susceptible the various materials are to picking up water. The moisture content of 
the insulation used in the heat leak tests may have been different. 


Table 2. Characteristics of the three best insulations. 



Fiberglas shoddy* 

Santocel 

Flameproof Dry Zero 

Heat leak, Btu per hr 

270 

175 

310 

Density, lb per cu ft 

5.8 

7.4 

1.9 

Durability 

Good 

Probably goodf 

Not wetted by water 

Inflammability 

Does not burn 

Does not burn 

Burns in oxygen 

Does not burn in air 

Facility of application 

Fairly easy 

Easy 

Difficult 


* From mixed yarn and scrap from forming, twisting and plying operations, 
t Detrimental feature is that it can be lost from cold box if leak occurs in unit. 


However, no direct measure of filtering efficiency has 
been attempted with either material. 

The filtration of solid C0 2 particles from liquid 
air streams proved to be no more difficult than con¬ 
ventional filtration of solids from liquids. However, 
C0 2 is soluble in liquid air to the extent of several 


parts per million, and of course this dissolved amount 
could never be removed by filtration. 

Experience showed that practically all the C0 2 in 
excess of solubility could be filtered out by commer¬ 
cial glass filtering cloths of the finest grade or by 
Fiberglas AA mat. 8 The filter cake could readily 














238 


MISCELLANEOUS EQUIPMENT 



SECTIONAL ELEVATION 

























































































































































































ANALYTICAL METHODS 


239 


be removed without warming by closing off the filter 
from the line and quickly venting it to the atmos¬ 
phere. Considerable flashing results from the de¬ 
pressurizing of the saturated liquid, and the flashing 
of liquid within and beyond the filter cake apparently 
disintegrates the cake and back-washes the filter ele¬ 
ment effectively. Repetition of this operation at regu¬ 
lar intervals was almost always successful in keeping 
a filter running indefinitely without warming. 

The detailed construction of a typical C0 2 filter 
is shown in Figure l. 5 

103 VALVES 

In general, commercial valves constructed of 
proper materials were suitable in the oxygen plants. 
For the periodic reversing of the exchangers in 
the low-pressure plants pneumatic quick-operating 
valves, either of the piston type or of the globe type, 
were used successfully at the warm end of the ex¬ 
changer, and at the cold end commercial check valves 
were found entirely suitable. 5 Both manual-operated 
and diaphragm-operated control and shutoff valves 
were used successfully on cold lines in the plants. In 
order to minimize the refrigeration loss resulting 
from the direct metal connection between the external 
air and the cold line, the valve stems and bonnets 
were always extended to an appropriate length with 
metals of reasonably low thermal conductivity, such 
as German silver, stainless steel, or various copper 
alloys. Valve-stem stuffing boxes always were placed 
outside the insulation casing for reasons of accessi¬ 
bility and to keep the packing material as warm as 
possible. Pure white asbestos and paraffined white 
asbestos were the packing materials most frequently 
used. 

10.4 TEMPERATURE measurement 

Copper-constantan thermocouples were generally 
used for the measurement of low temperatures. These 
thermocouples were used in the conventional fashion 
and conventional accuracy was obtained. Calibration 
of the couples at low temperatures could be made 
without undue difficulty at the vaporization tempera¬ 
ture of commercial solid C0 2 and at the boiling point 
of pure oxygen. The thermocouples were generally 
used with indicating or recording potentiometers. 

For more simple reading of temperature, a com¬ 
bination vapor-pressure and gas-pressure dial ther¬ 
mometer using oxygen or nitrogen was developed 
and placed on a production basis through co-opera¬ 


tion with a manufacturer. 6,9 Later, dial thermome¬ 
ters of various types were purchased from other 
manufacturers. The usual accuracy and dependa¬ 
bility of pressure-actuated dial thermometers was ob¬ 
served. 

10 5 ANALYTICAL METHODS 

In the development of oxygen plants several spe¬ 
cial analytical problems arose. The principal prob¬ 
lems were as follows. 

1. The determination of percentage of oxygen in 
gas mixtures, especially the analysis for purity in 
oxygen products. 

2. The determination of C0 2 content in air in the 
range from 400 ppm down to 10 ppm or less. 

3. The determination of hydrocarbons, especially 
acetylene, in air in the range from 5 ppm down to 
0.1 ppm or less. 

10 5 1 Oxygen Analysis 

Analysis for oxygen in gases was carried out with 
the conventional Orsat method. For the accurate 
measurement for oxygen purities in the range from 
97 to 100%, a measuring burette with a suitably 
extended scale in this range was employed. The 
oxygen absorbent used was copper metal washed with 
a solution consisting of one part of aqua ammonia 
and one part water, saturated with ammonium chlo¬ 
ride. This mixture can also be used as the confining 
liquid in the measuring burette in analyzing high 
purity oxygen, and an especially convenient appara¬ 
tus employing these principles is commercially avail¬ 
able. A description and appraisal of these methods 
has been given. 4 

For the continuous indication and recording of 
oxygen partial pressure, the novel Pauling meter was 
developed. (See Chapter 14.) 

10 5 2 Analysis of C0 2 in Air 

The accurate determination of C0 2 in air in the 
range from the normal concentration in atmospheric 
air (about 340 ppm) down to the lowest measurable 
concentrations was of great importance in the engi¬ 
neering evaluation of various possible schemes of 
removing the C0 2 from the compressed air fed to 
oxygen separating plants. Two analytical methods 
were used for routine tests and a third method was 
developed as the absolute standard used for calibra¬ 
tion of the other two. 

The absolute standard adopted 8 was a titrimetric 




240 


MISCELLANEOUS EQUIPMENT 


method in which the C0 2 is absorbed in standard 
dilute barium hydroxide and the excess alkali is 
back-titrated with dilute hydrochloric acid. Repeated 
samples of the air to be tested are drawn into a sample 
bottle containing the measured standard alkali, each 
successive sample being removed by evacuation after 
absorption of the C0 2 . The alkali is titrated in place 
in the sample bottle. This method avoids the errors 
introduced by exposure of the alkali to laboratory air. 
When the C0 2 concentration is very low an unduly 
large total gas sample must be taken. In this case it 
is convenient to condense out the C0 2 on the surfaces 
of a coil immersed in liquid air and then to evaporate 
the C0 2 into a small volume of air by warming the 
coil. 

One of the methods used for routine determina¬ 
tions is a colorimetric method. 1 This method de¬ 
pends upon the reduction by C0 2 of the color in¬ 
tensity of the solution of the sodium salt of phenol- 
phthalein. The procedure consists of the agitation of 
a measured volume of air with a definite volume of 
the indicator solution, followed by a measurement of 
the change in monochromatic light transmission of 
the solution. Great sensitivity can be obtained by 
suitable choice of the concentrations of alkali and 
phenolphthalein, and of the ratio of gas sample vol¬ 
ume to reagent volume. The method is capable of 
producing satisfactory precision only if considerable 
care is taken both in sampling and in carrying out the 
analysis. 

The second routine method was the use of the 
Pfund gas analyzer, which was developed under 
Division 17, NDRC. This instrument utilizes the 
infrared absorption characteristics of C0 2 and has 
proved to be completely satisfactory for the continu¬ 
ous analysis of gas samples. The meter is very sensi¬ 
tive, gives rapid readings, and, except for some un¬ 
certainty at CO -2 concentrations of 15 ppm or less, 
is capable of considerable accuracy. 8 

10 5 3 Low Concentrations of 

Hydrocarbons in Air 

The need for a method of analyzing for very low 
concentrations of hydrocarbons in air arose from 
the fact that light hydrocarbons, especially acetylene, 
present in atmospheric air tend to accumulate in the 
liquid air distillation apparatus and create serious 
explosion hazards. In order to develop methods for 
removing these hydrocarbons from the air feed to 
oxygen separation plants, a suitable analytical method 
was required to determine the extent of concentration. 


The procedure adopted for acetylene is a colori¬ 
metric method depending upon the formation of 
cuprous acetylide, which is red in color, in the reac¬ 
tion between a cuprous salt and acetylene. 7 A meas¬ 
ured gas sample is reacted with measured quantities 
of standard reagents and the monochromatic light 
transmission of the resulting solution is measured. 
The method is standardized using known mixtures of 
acetylene prepared by dilution. 

The method used for other hydrocarbons involves 
condensing the air sample in a trap cooled with liquid 
air boiling under reduced pressure, removing the at¬ 
mospheric gases by evacuation at normal liquid air 
temperatures, and allowing the remaining conden¬ 
sables to warm to room temperature and measuring 
the pressure remaining in the system. 7 This method 
is of value only if certain assumptions can be made 
as to the identity of the condensable material. The 
method can be extended by employing it to concen¬ 
trate the hydrocarbons, and then analyzing the hydro¬ 
carbons by conventional methods of gas analysis. 



Figure 2. Soda lime depletion apparatus. 


10 5 4 Field Method for Determining 
Depletion of Soda Lime 

An apparatus was developed for use in the field 
to test the degree of depletion of soda lime used as 
an absorbent for C0 2 in rebreather apparatus. The 
specifications for the apparatus required that it be 














ANALYTICAL METHODS 


241 


easily portable, very simple to use, as rugged as 
possible, and capable of accuracy within at least 
20%. It was also desirable that the apparatus be 
suitable for measuring the depletion of Baralyme, a 
commercial preparation used as an alternative for 
soda lime. 

The simple apparatus shown in Figure 2 was de¬ 


veloped. 8 A soda lime or Baralyme sample from 
scoops of standard size is placed in the water-filled 
apparatus, and a fixed quantity of concentrated hy¬ 
drochloric acid is added. The amount of C0 2 evolved 
is an index of depletion and is read directly on the 
calibrated collection chamber. Certain corrections for 
water temperature are made. 



Chapter 11 

OXYGEN GENERATION FROM REGENERATIVE CHEMICALS 

By T. A. Geissman a 


11 1 INTRODUCTION 

1111 Salcomine and Related Materials 

R egenerative chemicals for oxygen production 
. gave promise of certain advantages for genera¬ 
tion at advanced bases. Certain co-ordination com¬ 
plexes are able to carry oxygen reversibly and oper¬ 
ate over convenient temperature and pressure ranges. 
The parent and first-known compound 40 of this 
type is salicylaldehyde ethylenediamine cobalt, since 
called “Salcomine.” It is noteworthy that of the 
hundreds of compounds prepared and tested in the 
search for a substance which would carry more oxy¬ 
gen than Salcomine and possess a greater rate of 
reaction and stability, none of the very few active 
compounds discovered possesses a structure differing 
from Salcomine in a fundamental way, all of them 
being substitution products of the parent and most 
of them being 3-substituted. Indeed, from the prac¬ 
tical standpoint, taking into account cost and avail¬ 
ability, Salcomine itself must still be considered the 
most suitable compound for widespread application, 
although some of its substitution products have prop¬ 
erties which make them peculiarly adaptable for cer¬ 
tain special uses. 

11 2 CHEMISTRY OF SALCOMINE 
AND RELATED COMPOUNDS 

1121 General 

The property of forming coordination complexes 
with metallic ions is common to a large variety of 
organic compounds. The ability of such complexes 
to combine with molecular oxygen and to release it 
without the occurrence of other changes is found in 
only a very few substances. Among these are the 
important metal-porphyrin-protein complexes, such 
as hemoglobin and hemocyanin, in which the rever¬ 
sible oxygenation serves as a means of oxygen trans¬ 
port within the living organism. The only other large 
class of substances showing this ability, along with 


a Professor of Chemistry at University of California at 
Los Angeles. From August 1943 until October 1945, Chemi¬ 
cal Director of the Central Engineering Laboratory, Univer¬ 
sity of Pennsylvania, Contract OEMsr-934. 


sufficient stability to give them practical importance, 
are a group of cobaltous complexes related to and 
exemplified by salicylaldehyde ethylenediamine co¬ 
balt, or Salcomine (I). 



The characteristic grouping in salicylaldehyde 
which is responisble for its ability to form chelated 
metallic compounds is the ortho -hydroxy aldehyde 
grouping (II), which can form complexes such as 
III in which M = metal. 




CH % 


O 




■M 


II III 

Structure II may be generalized to include those 
compounds which are not simple o-hydroxy alde¬ 
hydes, like IV, but which form metallic complexes 
such as V. 



IV V 

In this general case, Y may be not only oxygen but 
also other elements or groups such as the imine group 
(as in primary or secondary amino groups, where 
YH is NH 2 or NHR) or sulfur (where YH is the 
sulfhydryl group). Substance X may be the oxygen 
atom of an aldehyde or ketone carbonyl group (as in 


242 







PREPARATION 


243 


II), the nitrogen of a SchifFs base (—CR = X is 
— CR = N—, as in I), or the nitrogen atom of a 
heterocyclic nucleus. Many other modifications of 
the structure I\ are possible, including a number 
in which the coordinating group — CR = X and 
—) H are not attached to an aromatic nucleus. 
Among such compounds are amino acids, keto acids, 
thio acids, enolizable /3-diketones, and imino deriva¬ 
tives of some of these. 

11 3 ACTIVE SALCOMINE 

ANALOGUES 

With the object of producing a substance of greater 
speed, capacity, and life than Salcomine, extensive 
studies were made. 

1. In order to learn what effect variations in the 
structure of the amine or polyamine might have upon 
capacity, rate, and life of the chelates, a number of 
cobalt complexes were made using amines other 
than ethylenediamine, combined both with salicyl- 
aldehyde itself and with substituted salicylaldehydes. 
In Table 1 are listed the compounds prepared using 
salicylaldehyde itself, various amines, and cobalt. In 
Table 2 are listed compounds containing substituents 
in the salicylaldehyde nucleus, amines other than 
ethylenediamine, and cobalt. 

2. The use of a variety of metals other than cobalt 
was studied with a number of organic compounds 
(see Table 3). In most cases the desired complexes 
were obtained readily, but in no case did a complex 


containing a metal other than cobalt have promising 
oxygen-carrying activity. In those few cases where 
oxygen uptake occurred, the result was the non- 
reversible (under conditions of operation) oxidation 
of the metal ion to a higher state. The compounds 
are listed in Table 4. 

3. The most important remaining direction in 
which improvement was sought lay in the use of 
substituted salicylaldehydes in place of salicylalde¬ 
hyde itself. The compounds tested are listed in 
Table 5. 

It will be seen that, of more than 200 substances 
examined, little or no oxygen-carrying activity is 
possessed by chelate compounds in which the funda¬ 
mental salicylaldehyde structure is varied, or in 
which diamines other than ethylenediamine are used, 
or in which the metal is other than cobalt. Certain 
Salcomine derivatives prepared from substituted sali¬ 
cylaldehydes were found to be active, and of these 
several 3-substituted compounds are superior to 
Salcomine in rate of oxygenation. With one excep¬ 
tion (3-fluoro-), however, they are inferior in sta¬ 
bility and in all cases have a lower oxygen capacity. 
In Table 6 are tabulated those chelates which com¬ 
pare favorably with Salcomine. 

11 4 PREPARATION 

The preparation of Salcomine and similar cobalt 
complexes is carried out by the sequence of reactions 
shown in the following equations: 

NaOH 


X 


CHO 

OH 


+ 


CHoNH, 

I ‘ 

CH,NH„ 


O CH=NCH 2 CH 2 N=CH 
OH HO 

X 


jA 

x 



CH 


,N=CHrf^^ 


O 


X 


Co ++ 


X = H Salcomine 
X — F Fluomine 
X = OCHs Methomine 
X = OC 2 H 0 Ethomine 





















244 


OXYGEN GENERATION FROM REGENERATIVE CHEMICALS 




N=CH 



Heat 


Active Salcomine + B 


Where B = H a O, GH.-.N, GH„N 


The important variables which affect the yield, 
capacity, and oxygenation rate of the final chelate 
are (1) the p H of the reaction mixture during the 
addition of the cobalt salt, (2) the volume of solution 
used, (3) the purity of the reagents used, (4) the 
presence or absence in the reaction mixture of such 
bases as pyridine, piperidine, or water (see below), 
and (5) the method of drying and activation used. 14 

When prepared in aqueous or aqueous-alcoholic 
solution, the chelates precipitate as crystalline hy¬ 
drates. In the presence of such stronger bases as 
pyridine and piperidine, complexes are obtained 
which contain one mole of the base per mole of 
chelate. In general, more uniformly active products 
can be obtained through the pyridinates or piperi- 
dinates, but the superiority of these over those pre¬ 
pared by way of the hydrates is usually not great 
enough to counterbalance the added expense and in¬ 
convenience of using the nitrogen bases. 

In any case, the water, pyridine, or piperidine is 
removed in the drying or activation process or in 
both. (See formula above.) 

Satisfactory methods for the preparation on a large 
scale of uniform hatches of active chelates were de¬ 
veloped by the Rumford Chemical Works. 34,52 


The chelates as usually prepared have capacities 
ranging from 85 to 95% of the theoretical. The 
differences are often due to impurities in the raw 
materials used. With carefully purified materials, it 
has been shown in small-scale preparations that prod¬ 
ucts having capacities of 95 to 99% of the theoretical 
can be obtained. 

11 4 1 Intermediates 53,54 ’ 55 

The greatest drawbacks to the adoption of Etho- 
mine and Fluomine for large-scale use is the inacces¬ 
sibility and high cost of preparation of 3-ethoxy- and 
3-fluorosalicylaldehyde. Salicylaldehyde itself is ob¬ 
tainable in the market in commercial quantities, but 
the ethoxy and fluoro compounds are not at present 
available, although considerable study has been de¬ 
voted to the problem of preparing these aldehydes 
economically and in quantity. 

3-Ethoxy salicylaldehyde (o-ethavan) has been 
available in small amounts as a by-product in the pro¬ 
duction of 3-ethoxy-4-hydroxybenzaldehyde (etha- 
van) by the Monsanto Chemical Co. This company 
has studied the problem of producing o-ethavan, and 
has recommended the method shown in the following 
equations: 


ogh 5 

<^S° h 

kk 

Ethacol 


OCH 5 

/NO CH.,CH=CH„ 


Ethacol allyl ether 


oc,h 3 

^S° h 

^^chxh=ch 2 


o-Allyl ethacol 


OCH, 

^S° H 

*%^JcH=CH CH 3 

o-Propenyl ethacol 


och 5 

Nj OH 

kk CHO 


o-Ethavan 

























PREPARATION 


245 


Table 1. 

Cobalt salicylaldehyde imines other than 

Salcomine. 


No. Amine 

Activity 

Remarks 

Ref 

1 Tetramethylethylenediamine 

Inactive 


2 

[(CH 3 ) 2 CNH 2 ] 2 

2 Methylenediamine 

Inactive 

Yellow complex 

2 

CH 2 (NH 2 ) 2 

3 Pentaerythritylamine 

Inactive 

Yellow complex 

3 

C(CH 2 NH 2 ) 4 

4 l,2-Diaminopropanol-3 

Inactive 

Yellow-brown complex 

3 

HOCH 2 CH-CH 2 

Active 1 % at 1 atm 


6 

nh 2 nh 2 

5 T riethylenetetriamine 

0 2 ; 3.42% (pressure) 

Inactive 

Complex not crystalline 

3 

(NH 2 CH 2 CH 2 NH-CH 2 -) 2 

6 Tetraethylenepentamine 

Inactive 

Complex not crystalline 

3 

NH(CH 2 CH,NH-CH,CH 2 NH 2 ), 

7 (//-Propylenediamine 

Inactive 

Schiff’s base not crystalline 

1 

rf/-CH s CH-CH*NH 2 

1 

nh 2 

Active 4.0% 


5 

8 /-Propylenediamine 

Inactive 


1 


/-CH 3 CH-CH 2 NH 2 


nh 2 

9 Yyin-Dimethylethylenediamine 
(CHaCHNH 2 ) 2 

10 Trimethylenediamine 

(CH 2 ) 3 (NH 2 ) 2 

11 Hexamethylenediamine 

(CH.),(NH 2 ), 

12 Nonamethylenediamine 

(CH 2 ) 9 (NH 2 ) 2 

13 Decamethylenediamine 

(CH 2 ) 10 (NH 2 ) 2 

14 Isopropylamine 

(CH 3 ) 2 CH-NH 2 

15 o-Phenylenediamine 

o-C«H,(NH 2 ) 2 

16 Benzidine 

NH 2 —C«H 4 ~N11. 

17 Ammonia 

NH 3 

18 Hydrazine 

' NH 2 - nh 2 

19 o-Aminophenol 

o-C«H 4 (OH)(NH 2 ) 

20 Diethylenetriamine 

NH(CH 2 CH 2 NH 2 ) 2 

21 None 

22 Bw-trimethylenetriamine 

NH(CH 2 CH 2 CH 2 NH 2 ) 2 
called “prtn” 

23 m-l,2-Diaminocyclohexane 

24 /ran j-l,2-Diaminocyclohexane 

25 Uiamino dipropyl ether 

0(CH 2 CH 2 CH 2 NH 2 ) 2 

26 l,3-Diaminopropanol-2 

(NH 2 CH 2 ) 2 CHOH 

27 2,6-Diaminopyridine 

28 2-Methylamino-l,3-diaminopropane 

CH 3 NH-CH(CH 2 NH 2 ) 2 

29 tran j-l,2-Diaminocyclopentane 

30 Ethanolamine 


Inactive 

Inactive 

Inactive 

Inactive 

Inactive 

Inactive 

Inactive 

Inactive 

Inactive 

Inactive 

Inactive 

Active (slow) 

Inactive 

Active 


Inactive 

Inactive 

Inactive 

Inactive 

Inactive 

Inactive 


Complex red, crystalline 1 

1 

10 

Complex crystalline 1 

Complex tarry 1 

Complex tarry 1 

1 

1, 5 or 
10 
1 

5 

5 

5 

Chelate yellow powder 5 

5 

11.9% in 8 days at 6 

85 psi 0 2 ; 1.5 hr at 100 C 
removed all but 3.4% of 
this 0 2 ; not reversible 

8 

8 

No definite complex isolated 9 

9 

Only cobalt salicylaldehyde 9 

isolated 

9 

10 
11 


NH 2 CH 2 OH 

31 Diaminoacetone 

32 T m-aminomethylmethane 

CH(CH,NH 2 ) 3 


Some preparations show activity 
Inactive 


12 

12 











246 


OXYGEN GENERATION FROM REGENERATIVE CHEMICALS 


Table 2. Cobalt complexes prepared from substituted salicylaldehydes and amines and polvamines other than Ethyl- 
enediamine. 


No. 

Substituted salicylaldehyde 

Amine 

Activity and remarks 

Ref 

1 

3-nitro 

1,2-diaminopropanol-3 

HO—CH 2 —CH—CH : , 

1 1 
nh 2 nh 2 

Yellow-brown inactive 

3 

2 

5-nitro 

1,2-diaminopropanol-3 

Inactive 

3 

3 

3-nitro 

6«-diethylenetriamine 

NH(CH 2 CH 2 NH 2 ) 2 

Inactive 

3 

4 

3-nitro 

triethylenetetriamine 

NH-CH 2 -CH 2 -NH 

Oily, inactive 

3 


I I 

ch 2 ch 2 

I I 

ch 2 nh 2 ch 2 nh 2 


5 

5-nitro 

triethylenetetriamine 

Oily, inactive 

3 

6 

3-nitro 

tetraethvlenepentamine 

NH(CH 2 CH 2 NH 2 CH 2 CH 2 NH 2 ) 2 

Red oil, inactive 

3 

7 

5-nitro 

tetraethylenepentamine 

Red oil, inactive 

3 

8 

3-formyl-4-hydroxy 

None 

Yellow. Active to water 

5 

9 

3-methyl 

fcu-trimethylenetriamine [prtn] 

Active. Not completely reversible 

6 



NH(CH 2 CH 2 CH 2 NH 2 ) 2 

Some inactive. Some preparations 6.5%. 




prtn 

8 



prtn 

6-7% at 150 psi 0 2 at room temp, 7.6% at 

100 psi 0 2 at 0 C; successive preparations 

9 

10 

5-methyl 

prtn 

6.9%. Only partially reversible 

6 

11 

3-methoxy 

prtn 

5.7%. Only partially reversible 

6 

12 

3-nitro 

prtn 

3.47% (175 psi 0 2 ). Reversible 

6 



Inactive, by treating active form with pyridine 

7 

13 

3-chloro 

prtn 

4.7% high press. Reversible 

6 

14 

5-nitro 

prtn 

1.5% weakly active 

6 

15 

5-chloro 

prtn 

<1% weakly active 

6 

16 

5-hydroxy 

prtn 

Inactive 

6 

17 

4-hydroxy 

prtn 

Inactive 

6 

18 

3-ethyl-4-hydroxy 

prtn 

1.25% weakly active 

6 

19 

3-ethyl-4-methoxy 

prtn 

5.6% in 2 hr at 175 psi 0 2 . Reversible 

6 

20 

3-allyl 

prtn 

Inactive 

7 

21 

4-methoxy 

prtn 

Some activity. Oxidizes while wet 

7 

22 

5-amino 

prtn 

Black, inactive 

8 

23 

3-ethyl-4-hydroxy-5-formyl 

prtn 

Not reversible. 3.6% at 1 atm, 

4.8% at 200 psi 0 2 

8 

24 

6-chloro 

prtn 

Br-yellow hydrate, si. activity up to 2.5% 

8 

25 

4-nitro 

prtn 

SI. active 

8 

26 

3-isopropyl-6-methyl 

prtn 

4.65% at 200 psi 0 2 deteriorates rapidly 

8 

27 

3-methyl-6-isopropyl 

prtn 

6.3% at 175 psi 0 2 . Not reversible 

8 

28 

3-chloro-5-tert. butyl 

prtn 

SI. active 

8 

29 

3-n propyl 

prtn 

Inactive 

8 

30 

3-phenyl 

prtn 

Inactive 

8 

31 

5-tert. butyl 

prtn 

No complex isolated 

9 

32 

4-ethoxy 

prtn 

Inactive 

9 

33 

4-hydroxy-6-methyl 

prtn 

7.3% at 225 psi 0 2 in 12 hr; then 4.5% at 

1 atm difficult to prepare, active 

9 

34 

4,6-dimethyl 

prtn 

Br-y, si. active 

9 

35 

3-methyl-6-chloro 

prtn 

3% at 150 psi 0 2 

10 

36 

5-carbomethoxy-6-hydroxy 

prtn 

Inactive 

10 

37 

3-ethyl 

prtn 

3.6% at 200 psi 0 2 , 2.7% at 1 atm. 

Very fast deterioration 

11 

38 

3-fluoro 

prtn 

4-5% but requires press. 

12 

39 

4-methoxy-6-methyl 

prtn 

Some activity 

9 









PREPARATION 


247 




Table 3. Chelates containing 

metals other than cobalt. 


No. 

Carbonyl compound 

Amine 

Metal 

Activity remarks 

Ref 

1 

Salicylaldehyde 

en* 

Fell 

Inactive 

1 





Inact., oxid. to Fe 111 

5 

2 

5-Bromosalicylaldehyde 

en* 

Mn 

Inactive 

1 

3 

Pyruvic acid 

en* 

Fell 

Inactive, ferrous state estab. by test 

1 

4 

Pyruvic acid 

d/-l,2-diaminopropane 

Fell 

Inactive. Fe 11 estab. by test 

1 

5 

Pyruvic acid 

o-phenylenediamine 

Fen 

Inactive 

1 

6 

Salicylaldehyde 

o-phenylenediamine 

Fen 

Inactive 

1 





None 

5 

7 

Vortmann’s sulfate 



None 

5 

8 

Phthalocyanine 


Fell 

Violet. None 

5 

9 

Quinaldinic acid 

• . • 

Fell • 

None 

5 

10 

Salicylaldehyde 

D'ethylenetriamine 

Fell 

None 

5 



NH(CH 2 CH 2 NH 2 ) 2 


Oxidized to FeUI 


11 

Salicylaldehyde 

o-aminophenol 

Fell 

None 

5 





Oxidized to FelH 


12 

2-Hydroxybenzamide 

... 

Fen 

None 

5 





Oxidized to Fe 111 


13 

2-Aminobenzaldehyde 

en* 

Fen 

Chelate not isolated 

5 

14 

Violuric acid 


Fen 

Inactive 

5 

15 

Picolinic acid 


Fen 

Hard to isolate. No conclusions 

5 

16 

Salicylaldehyde 

en* 

Mn 

Active, oxidized 

5 

17 

Salicylaldehyde 

Diethylcnetriamine 

Mn 

Yellow. None 

5 

18 

Salicylaldehyde 


Cu 

None 

5 

19 

Salicylaldehyde 

en* 

Cu 

None 

5 

20 

Salicylaldehyde 

D'ethylenetriamine 

Cu 

None 

5 

21 

Diazoaminobenzene 

. . • 

Ni 

None 

5 


/\n=N -NHr^Ni 


V 

22 Salicylaldehyde 


Ni 

None 

5 

23 Salicylaldehyde 

en 

Ni 

None 

5 

24 Salicylaldehyde 

en 

Vanadyl 

None 

5 

25 Salicylaldehyde 

prtn 

Fell 

No complex isolated 

9 

26 Salicylaldehyde 

T rimethylenediamine 

Cu 

Inactive 

11 


* Ethylenediamine [en] (NH 2 CH.,CH 2 NH 2 ) 


The yields to be expected in this process are as 
follows, o-allyl ethacol on ethacol consumed, 81% 
of theory; fraws-o-propenyl ethacol on o-allyl ethacol, 
70% of theory; o-ethavan on fra/w-o-propenyl etha¬ 


col, 70-73% of theory; overall yield, 40-41% of 
theory. 

3-Fluorosalicylaldehyde has been prepared by the 
reactions shown in the following equations: 


och 3 


och 3 

N;C1- 


The maximum yields obtained in these reactions 

are: o-anisidine-» diazonium horofluoride, 90%; 

diazonium horofluoride -» o-fluoroanisole, 65%; 

o-fluoro-anisole-> o-fluorophenol, 86% ; o-fluoro- 

phenol-> 3-fluorosalicylic acid, 55%; 3-fluoro- 

salicylic acid -> 3-fluorosalicylaldehyde, 55% ; 

overall yield, 15%. 


och 3 


N + BF; 

2 4 


och 3 

k^ 


OH 

f 

k^ 


F 

X\° H 

^^JcOOH 


F 

X\° H 

^JcH=N 



ch 3 


F 

^^|OH 





































248 


OXYGEN GENERATION FROM REGENERATIVE CHEMICALS 


Table 4. Cobalt complexes prepared from carbonyl compounds other than salicylaldehydes or substituted salicylaldehydes 
and amines and polyamines of all types. 


No. Carbonyl compound 
1 2-Hydroxyacetophenone 


2 2,-4-dihydroxyacetophenone 

3 2-hydroxy-propiophenone 

4 2-hydroxy-S-methyl-acetophenone 

5 2-hydroxy-4-methyl-acetophenone 

6 2-hydroxy-3-nitro-acetophenone 

7 Ethylene fcw-thioglycolic acid 

(-CH 2 S-CH 2 COOH) 2 

8 Glyoxal bw-o-hydroxyanil 



9 Formyl camphor 
CllHl«0 2 

10 Formyl camphor 


11 Pyruvic acid 

CHsCOCOOH 

12 Pyruvic acid 

13 Pyruvic acid 

14 Picolinic acid 


COOH 

15 2-aminobenzaldehyde 

16 8-hydroxyquinoline 

17 2-hydroxybenzamide 

18 2-aminophenol 

19 Acetylacetone 

CH 3 COCH 2 COCH 3 

20 Ethyl acetoacetate 

CH 3 C0CH 2 C00Et 

21 Methyl acetoacetate 

CH 3 COCH 2 COOCH 3 

22 Acetylacetone 

23 2-hydroxyacetophenone 



24 Naphthazarin 

25 1,2-cyclohexanedione dioxime 


a NOH 

NOH 


26 1,2-cyclopentane-dione 

27 2-5-dihydroxy acetophenone 


Amine Activity and remarks Ref 

Ethylenediamine [en] 4.0%, slow, and only under 200 psi 1 

NH 2 CH 2 CH 2 NH 2 

Red, cryst., some activity 5 

Ca. 2%, difficult to prepare active sample 7 
4.53% at 100 psi 0 2 13 

en Slight 1 

Red. None 5 

en Could not form chelate 4 

Cryst. inactive 5 

en Red. 1.0% (?). 200 psi 0 2 4 

en Brown. Inactive 4 

en Red. Inactive. Chelate not analyzed 4 

... Violet, cryst., inactive 4 

... Inactive 3 


en 


o-phenylenediamine 

O NH, 
NH, 


en 


Inactive 

Inactive 


Inactive 


<f/-l,2-diaminopropane 

o-phenylenediamine 

None 


Inactive 
Inactive 
Orange. None 


2 

2 


1 

1 

1 

5 


en Red, cryst. None 5 

None Yellow. None 5 

None Yellow. None 5 

Brown-pink. None 5 

None Cryst. None 5 

None Cryst. None 5 

None Cryst. None 5 

en Cryst., active, eventually oxidizes 5 

prtn Inactive 6 

Active 3.22%. Deteriorates rapidly 7 

... SI. activity 8 

SI. activity 8 


en ... SchifFs base decomposes 9 

en ... Could not obtain chelate 12 








OXYGENATION-DEOXYGENATION REACTION 


249 


No.Carbonyl compound 

28 Dithio oxamide 

NH 2 CSCSNH 2 

29 fcij-(o-hydroxybenzal) acetone 



30 2-orthohydroxyphenyl quinoline 

31 1-orthohydroxyphenyl isoquinoline 

32 3-formy l-4-hydroxy-6-methy 1-quinaldine 

33 3-formyl-4-hydroxy-quinaldine 

OH 



35 2-hydroxy-3-formyl-4,6-dimethyl-pyridine 


CH. 



36 2-hydroxyacetophenone 

37 2-hydroxyacetophenone 

38 2-hydroxy-3-ethoxy-acetophenone 

39 2-hydroxy-3-methoxyacetophenone 

40 2,2-ti>-o-hydroxyphenyl-6,6-dipyridine 



H 


Table 4 ( Continued ) 

_ Amine _ Activity and remark s 

• • • Complex decomposes 

... Inactive 


... Inactive 

•.. Inactive 

en o-r. cryst. inactive 

en Yellow, inactive 


en 


Yellow, inactive 


en 


Complex not obtained 


1,2-diaminopropane Inactive 

T rimethylenediamine Inactive 

(CH 2 ) 3 (NH 2 ) 2 

en ... 1% (pressure) 

en Active, requires high pressure 0 2 

... Red, cryst., inactive 


Ref 

12 

12 


13 

13 

13 

13 


13 


13 


13 

13 

13 

13 

13 


115 OXYGENATION-DEOXYGENATION 
REACTION 

A thorough study has been made of the reaction 
between oxygen and cobalt chelates of the Salcomine 
type. The aspects of the reaction examined in detail 
are as follows. 

1. The heat of the reaction 

2 chelate -f- 0 2 ^ chelate — 0 2 — chelate 


2. The equilibrium between oxygen and the che¬ 
late. 

3. The rate of the oxygenation reaction, with re¬ 
spect to the oxygen pressure and the temperature. 

4. The crystal structures of the various forms (ac¬ 
tive, inactive, oxygenated, deteriorated) of several 
chelates, determined by means of X-ray studies. 

5. The magnetic properties of the oxygenated and 
oxygen-free chelates. 












250 OXYGEN GENERATION FROM REGENERATIVE CHEMICALS 


Table 5. Cobalt salicylaldehyde ethylenediamines containing substituents in the salicylaldehyde nucleus. 

No. Substituted salicylaldehyde 

Activity 

Remarks 

Ref 

1 4-hydroxy 

Inactive 

Structure of chelate doubtful 

3 


4% 

Stable, red cryst. 

5 

2 4-methoxy 

3.0% 

Active if activated at 120-130 C 
Inactive after heating at 160 C 

3 


4.34% 

Requires high press. Reversible 

6 

3 5-hydroxy 

Turns black in air, but inactive after 
deoxygenation 




5.2% (pressure) 

Not reversible 

8 

4 3-chloro 

1.9% 

Slow 

3 


Inactive 

Forms pyridine peroxide 

6 

5 5-ethyl 

4.2% 

Comparable to Sal. 

3 

6 3,6-dimethyl 

Inactive 


3 

7 4,6-dimethyl 

Inactive 


3 

8 5-methyl 

2.7% on preparation in 50% ale. 

Preparations from Na salt of 

Schiff’s base inactive 

1 

9 4-methyl } 

6-methyl j 

1.56% ; inactive in air 

Mixture of aldehydes used 

1 

4-methyl 

Inactive 


8 

10 3-methyl 

Inactive 


1 


Inactive 


6 

11 3-methoxy 

Active, fast, reversible “Methomine” 


1 


Active, very rapid to theoretical capacity 


8 

12 3-methoxy-5-nitro 

Inactive 


— 

13 5-bromo 

Inactive 


1 

14 3-nitro 

3.83% 

Fast, sensitive to water 

1 

15 5-nitro 

Inactive 


1 


1.5% 

Red cryst., stable 

5 

16 2-hydroxy-1 -naphthaldehyde 

Inactive 

1 

17 3-carboxy 

Inactive 

Chelate tarry ; structure doubtful 

4 


1% 

Red; cryst. 

12 

18 3,5-dibromo 

Inactive 

4 

19 5-chloro-6-methyl ) 
6-chloro-5-methyl ) 

Inactive 

Mixture of aldehydes used 

4 

20 3-ethoxy 

Active, fast, reversible 

Ethomine 

2 

21 3-propoxy 

3.5%, fast 

Hygroscopic 

2 

22 5-ethoxy 

Inactive 


2 

23 3-bromo 

Inactive 

Yellow to red-brown. No color 
change on drying at high temp. 

2 

24 3-isopropyl-6-methyl 

Inactive 


4 


Inactive 


8 

25 3,5-dimethyl 

Inactive 


4 

26 3,5-di-tcrt-amyl 


Poor yields; abandoned 

4 

27 3-tert -amyl 

Inactive 

4 

28 3-methyl-5-/cr/-amyl 

Inactive 


4 

29 3-chloro-5-tcrt butyl 

Inactive 


4 


Slightly active 


8 

30 3-bromo-5-fcrf butyl 

Inactive 


4 

31 3-isopropyl-5-chloro-6-methyl 

Inactive 


4 

32 3-n-butoxy 

3.3%, very fast 

Cryst. 

4 

33 5,6-dimethyl 

Inactive 

Mixture of aldehydes used 

4 

4,5-dimethyl 



34 S-tcrt butyl-6-methyl ) 
4-methyl-5-tcrt butyl j 

Inactive 

Mixture of aldehydes used 

4 

35 3-formyl-4-hydroxy 

6%, slow 

Constitution of chelate unknown 

5 

36 5-chloro 

Inactive 

Brown, cryst. 

5 

37 4-nitro 

1.5% 

Red, cryst. stable 

5 


4.2% 

Reversible 

8 

38 5-methoxy 

Inactive 


6 

39 3-allyl 

Inactive ( ?) 

Some preparations show some activity 

7 

40 3-ethyl-4-methoxy 

Inactive 

7 

41 3-ethyl, 4-hydroxy, 5-formyl 

2% at 1 atm 0 2 5.74% under press. 

Deteriorates; very insoluble 

7 

42 5-amino 

1% at 1 atm 2% (pressure) 

Black 

8 

43 6-chloro 

Inactive 


8 








OXYGENATION-DEOXYGENATION REACTION 251 


Table 5 ( Continued ) 

No. 

Substituted salicylaldehyde 

Activity 

Remarks 

Ref 

44 

3-methyl-6-isopropyl 

Inactive 


8 

45 

3-phenyl 

Inactive 


8 

46 

3-n-propyl 

Inactive 


8 

47 

5-carbomethoxy-6-hydroxy 

Inactive 


10 

48 

3-fluoro 

Active, very fast reversible 

Fluomine 

12 

49 

5-propionic acid 

Inactive 


12 

50 

6-methoxy 

Inactive 


13 

51 

4-hydroxy-6-ethyl 

Inactive 


13 

52 

6-methyl 

1.5% (pressure) 


12 

53 

3-ethyl 

Inactive 

Cryst. 

13 

54 

5-fluoro 

Active (theor.) very slow 

Red-brown 

13 


Table 6. Active Salcomine derivatives: Co-X-Sal-en*. 

Chelate 

Oxygen capacity 

Remarks 

Co-Sal-en 

Theoretical capacity! 

Salcomine! 

Co-3-OEt Sal-en 

Theoretical capacity! 

Ethomine! 

Co-3-OMe Sal-en 

Theoretical capacity! 

Methomine! 

Co-3-NO-.- Sal-en 

3.83% 

Fast, sensitive to water 

Co-3-F Sal-en 

Theoretical capacity! 

Fluomine! 

Co-3-OPr Sal-en 

3.5% 

Fast, deteriorates rapidly, 



sensitive to FRO 

Co-3-OBu Sal-en 

3.5% 

Fast, deteriorates rapidly 

Co-4-OH Sal-en 

4% 


Co-4-OMe Sal-en 

4.34% 

Requires high pressure 

Co-5-Et Sal-en 

4.2% 


Co-4-NCh Sal-en 

4.2% 


Co-5-F Sal-en 

Theoretical capacity! 

Very slow 


* Co-X-Sal-en is an abbreviation for X-substituted-salicylaldehyde ethylenediamine cobalt. 

t The theoretical capacities of 1 atom of O per molecule of chelate have been realized on carefully made laboratory preparations, although 
the usual materials manufactured on a semi-plant scale have capacities of 90—95% of the theoretical. 

X The substances to which trivial names have been assigned are those which were prepared and tested on a large scale for the purpose of 
gathering data for engineering design of practical operating units. 

6. Changes in the structure of Salcomine crystals 
during the course of oxygenation (determined hy 
means of photomicrographs). 

7. The mechanism of the reaction, deduced from 
the data obtained by the above experimental proce¬ 
dures. 

ii 5.i Heat of Reaction 

Chelates of the diamine type have a AT/ of 18-21 
kcal per mole of oxygen, while the single example of 
the triamine (prtn) type has a lower A H, about 15 
kcal per mole. 

ii-5.2 Equilibrium Vapor Pressure of 

Oxygenated Chelates 

By raising slowly the temperature of an oxygen¬ 
ated sample of chelate at constant pressure and meas¬ 
uring the oxygen evolved at a series of temperatures, 
a plot of composition vs temperature can he con¬ 


structed. Two typical plots obtained in this way, for 
Ethomine and Fluomine, 51 are shown in Figures 1 
and 2. 

ii.5 . 3 Rate of Oxygenation Reaction 

Typical absorption rate curves are shown in Fig¬ 
ures 3 and 4. The data are taken by the following 
generalized procedure. 

A sample of the deoxygenated chelate is brought 
to a constant temperature, and oxygen (or air) is 
admitted to a desired pressure. Oxygen (or air) is 
then admitted to the system at such a rate as to main¬ 
tain the initial pressure over the compound, the rate 
of admission, and thus the rate of absorption, being 
measured by the change in volume or of pressure of 
a calibrated reservoir. It is seen from Figure 4 that 
the rate of absorption is influenced hy the oxygen 
pressure. This is shown more clearly in Figure 5 
in which the (second-order) absorption rate constant 
for Fluomine is plotted vs the oxygen partial pressure. 










252 


OXYGEN GENERATION FROM REGENERATIVE CHEMICALS 



0 10 20 30 40 50 60 70 80 90 100 

TEMP C 


Figure 1. Equilibrium curves at constant pressure. Eth- 
omine. 



Figure 3. Typical absorption rate curve. Co-Sal-en at 
25 C, 760 mm0 2 . 



Figure 2. Equilibrium curves at constant pressure. Flu- 
omine. 



20 C. 















WT •/. OXGEN ABSORPTION 


OXYGENATION-DEOXYGENATION REACTION 


253 



Figure 5. Fluomine. Second-order absorption rate. Con¬ 
stant temperature vs pressure (T = — 40 C). 


Since the equilibrium vapor pressure of oxygen 
over the oxygenated chelates increases with temper¬ 
ature, it follows that the rate of absorption will show 
a maximum at a temperature which is characteristic 
of the compound. Typical curves showing this effect 
in the case of Ethomine are given in Figure 6. In 


x 



Figure 6. Optimum absorption temperature of Etho¬ 
mine. Air pressure: atmospheric. Air rate: 3 cfh/40.7 
g, J^-in. tube unit. 


Table 7 are given optimum absorption temperatures 
for several compounds. 


Table 7. Optimum absorption temperatures for several 
compounds. 


Compound 

Optimum absorption temperature 

Salcomine 

5 C 

Ethomine 

25 C 

Fluomine 

35 C 


11 5 4 Crystal Structure of the 

Chelates 22 ’ 24 ’ 25 

Salcomine has been studied intensively by means 
of powder photographs. 23 The structure is relatively 
simple (Figure 7). It will be noted that there are 
holes running through the structure parallel to do. 
Possibly oxygen may pass from one cavity to another 
and thus be transferred by a sort of diffusion from 
an oxygenated molecule to an unoxygenated one. 
Two other active derivatives of Salcomine, namely, 
Fluomine and CO-o-hydroxyacetophenon-en, yield 
powder photographs strikingly similar to those from 
Salcomine itself. If the structures are essentially the 
same (coplanar layers of molecules) the chief effect 
of the substituents will be to expand the structure in 
the b 0 direction, with the result that the holes in the 
structure are slightly larger in the case of these 3- 
substituted compounds than in Salcomine. 

The size of these passages through the structure 
is evidently not the only factor in determining the 
speed of oxygenation of a given chelate, since the 
3-chloro-derivative of Salcomine, which would be 
expected to show holes larger than those in Fluomine, 
is inactive; and CO-o-hydroxyacetophenone-en, com¬ 
parable in structure to Fluomine, is much slower in 
its rate of oxygenation. 

11 5 5 Magnetic Properties of the Cobalt 

Chelate 10 ’ 11 ’ 19 ’ 20 ’ 24 

Measurements have been made of the magnetic 
susceptibilities of many forms of Salcomine and its 
analogues, including such modifications as solvated 
complexes, active and inactive forms, and oxygenated 
forms. The results can be summarized as follows. 

1. Active diamine complexes, for example, Salco¬ 
mine and Fluomine, contain one unpaired electron in 
the oxygen-free state, and are essentially diamagnetic 
when oxygenated to the 2/1 oxide. The paramagne¬ 
tism shows a linear decrease with increasing per cent 
of oxygenation between these extremes. 













254 


OXYGEN GENERATION FROM REGENERATIVE CHEMICALS 



Figure 7. Crystal structure of Salcomine. 


2. Active triamine (prtn) complexes contain three 
unpaired electrons before oxygenation, the oxygen¬ 
ated (1/1) form having one unpaired electron. 

3. Some inactive forms of diamine complexes show 
three unpaired electrons per cohalt atom. 

4. Solvated diamine complexes show one or three 
unpaired electrons. Occasionally a sample showing 
two unpaired electrons has been encountered, and 
this has been assumed to he the result of the presence 
of a mixture of forms. 

In the case of the diamine complexes, the mag¬ 
netic properties of the active forms constitute good 
evidence that the molecule is coplanar, the four filled 
coordination positions of the cobalt atom being situ¬ 
ated at the corners of a square. 

11 5 6 Changes in the Gross Structure of 
Salcomine Crystals during Cycling 

A series of photomicrographs (X125) have been 
made of a single, active crystal of Salcomine, 
0.29 X 0.03 mm, through four cycles. Cycling was 
produced by oxygenating the crystal under 1 atm 
pressure of 0 2 , and deoxygenating upon a hot stage 
on the microscope. 

The following observations were made. 

1. Oxygenation splits and bends the crystal. 


2. Simultaneous with this rupture, there is an in¬ 
crease in the length and decrease of the width of the 
crystal. The areas remain constant. 

3. On deoxygenation, the crystal tends to return 
to its original form. 

Figure 8 shows an enlargement (X2.000) of a 
crystal which has been cycled four times. It shows 
the pattern of cracks developing which have not yet 
reached the stage of actual separation of the finer 
fragments. These fragments have a diameter of ap¬ 
proximately 5 X 10~ 4 mm. 

Since the ability of this material to hold oxygen 
depends upon the cooperation of two molecules ar¬ 
ranged in a very specific lattice, it would appear that 
this particle size reduction may be an important 
factor in capacity reduction on cycling; and it may 
account in part for the observation that loss in oxy¬ 
gen capacity upon deterioration always exceeds the 
loss in the amount of chemically intact Salcomine 
in the same sample. 

n 5 7 Mechanism of the Oxygenation 

Reaction 13 ’ 20 ’ 21 ’ 22 

The mechanism of the reaction between Salcomine, 
et cetera, and oxygen has been studied with the aid 
of the experimental methods outlined in the fore- 




































OXYGENATION-DEOXYGENATION REACTION 


going sections, the principal source of information 
being the analysis of the dependence of the rate of 
the reaction upon chelate composition, temperature, 
and oxygen pressure. 



Figure 8. Enlargement (x2,000) of a crystal which has 
been cycled four times. 


For Salcomine and Ethomine, the reaction fol¬ 
lows the first-order law. A typical plot of some rate 
data is shown in Figure 9, in which it is seen that the 
first order law is followed closely except at very low 
and very high degrees of oxygenation. 13 Figure 10 
shows a similar plot in which it is apparent that the 
order of the reaction is not modified by changes in 
the oxygen pressure. 

For Fluomine, the reaction at low oxygen pres¬ 
sures appears to he second order with respect to the 
chelate, although at high oxygen pressures there is 
some indication that it is first order. There is also 
an indication that, at an oxygen pressure at which 
the reaction is second order at low temperature, it 
may become first order at higher temperatures. 

It has been established that, in the case of all of 
the diamine chelates, a marked induction period in 
the uptake of oxygen appears at high temperatures 
(above the optimum temperature). 


255 



Figure 9. Typical plot of rate data. Ethomine (15 C) 
Reaction order test. 13 



Figure 10. Typical plot of rate data. Ethomine ( — 10 C). 
First order test. 21 


From the practical standpoint, the existence of an 
induction period would limit the useful range over 
which the compound can he oxygenated in the course 
of a complete cycle of absorption and desorption. It 
would lie desirable to carry out the deoxygenation to 
such an extent only as to leave the desorbed com- 

















256 


OXYGEN GENERATION FROM REGENERATIVE CHEMICALS 


pound partially oxygenated, so that upon reoxygena¬ 
tion the induction period would not appear. In other 
words, that portion of the absorption rate curve which 
is essentially a straight line would be used in a cycle. 

11 6 ENGINEERING EVALUATION OF 
SALCOMINE AND ITS 
CONGENERS 

11 61 General Introduction 

For the design of a unit for the production of oxy¬ 
gen by means of Salcomine, Ethomine, or Fluomine, 
one of the most important factors is the heat load 
for which provisions must be made over a complete 
cycle of operation. Since during oxygenation an 
amount of heat is evolved equal to about 19 kcal per 
mole of oxygen absorbed, the temperature of the ab¬ 
sorbent would rise sharply unless some means were 
provided for dissipating this heat. If this heat were 
not removed and the temperature of the absorbent 
allowed to rise, the rate of oxygenation would de¬ 
crease because of the increase in back pressure of 
oxygen over the oxygenated chelate. This could be 
overcome by using an initial oxygen (or air) pres¬ 
sure so high that a large excess driving force would 
always be present, but there are reasons why this is 
impractical. The most satisfactory procedure is to 
use a suitable heat exchanger in which controlled 
removal of heat during oxygenation and controlled 
addition of heat during desorption can be accom¬ 
plished. 

Important information about the practical utili¬ 
zation of these absorbents has been gained in ex¬ 
periments carried out in apparatus which compares 
closely with large-scale equipment in heat-transfer 
and pressure-drop characteristics, and in which re¬ 
peated cycling can be carried out, but which is con¬ 
structed on a smaller scale. Most of the testing of 
the various chelates which were selected for intensive 
study was carried out in apparatus holding from 
about 0.1 to 35 lb of chelate and in which provision 
was made for automatic control of fixed cycles which 
could be repeated for any desired length of time. 

117 THERMAL PROPERTIES OF 
SALCOMINE 30 

The important thermal properties of Salcomine, 
et cetera, are (1) the specific heat, (2) the thermal 
conductivity, and (3) the heat of reaction. The 
last of these has already been discussed. 


The specific heat of Salcomine w r as determined 
calorimetrically, and found to he 0.24 Btu per lb per 
degree Fahrenheit. The specific heats of Ethomine 
and Fluomine have not been determined hut are pre¬ 
sumably about the same. 

The thermal conductivity of Salcomine obviously 
depends upon its state of aggregation, whether it is 
in powder or granular form, and the degree of com¬ 
pression of the granules. Attempts have been made 
to increase the thermal conductivity (and heat ca¬ 
pacity) of Salcomine by the addition of metallic 
powders 28 in Table 8 are given the thermal con- 


Table 8. Thermal conductivity of various granules and 
pressed cakes. 


Material 

Thermal cond., k 

Spec grav 

Salcomine 10 to 20 mesh 

0.0366 

0.65 

Salcomine cake pressed 3,640 psi 

0.0990 

1.10 

3,640 psi plus 10% aluminum 

0.105 

1.23 

3,640 psi plus 10% bronze 

0.098 

1.18 


ductivity, k, in Btu per (hr) (sq ft) (° F) per ft, 
of various granules and pressed cakes. These data 
were obtained from steady state measurements at an 
average temperature of about 35 C. 

It is apparent from these data that the thermal 
conductivity is very low and is not appreciably in¬ 
creased by metallic additives. The considerable in¬ 
crease in weight resulting from adding metal pow¬ 
ders, coupled with a reduced weight of chelate per 
pound of charge, overbalances any small advantage 
that might be gained by such additions. 

Attention was also directed to an examination of 
the heat transfer properties of beds of Salcomine. 
Theoretical and experimental investigations have 
shown that the heating or cooling time of a cylindri¬ 
cal bed of Salcomine is proportional to the square of 
the radius of the cylinder. In Figure 11 are shown 



Figure 11. Heating and cooling curves of cylindrically 
packed beds of Salcomine. 








METHODS OF OPERATION OF THE CYCLE 


257 


heating and cooling curves of cylindrically packed 
beds of Salcomine in }4-in. and 1-in. tubes. It is at 
once apparent that the use of small diameter tubes 
(or short conduction paths) offers a distinct advan¬ 
tage. The advantage, moreover, is much greater than 
can be shown by such data as these, since in a bed 
in which a long conduction path exists, the chelate 
near the heating surfaces must be maintained at a 
high temperature for an extended period in order 
to allow the heating of material distant from the 
heating surfaces, thus causing rapid and extensive 
deterioration in activity. 


11 8 METHODS OF OPERATION 
OF THE CYCLE 

Since Salcomine, Ethomine, and Fluomine are best 
oxygenated at a low temperature under pressure, and 
deoxygenated at elevated temperatures under re¬ 
duced pressure, the necessity for cooling and heating 
the considerable mass of the reactor in which the 
granules are packed imposes the requirement for 
furnishing and removing much more heat than that 
of the reaction alone. It would be a distinct advan¬ 
tage if a system could be devised whereby the chelate 
alone would have to be heated and cooled, or in 
which the heat of the reaction could be stored in the 
chelate itself, enough pressure being used in the latter 
case to give rapid oxygenation at a relatively high 
temperature. Systems utilizing these principles of 
operation have been studied experimentally, and are 
described in the following sections. 

11 81 The Fluidized System 

Fluidized operation consists of suspending pow¬ 
dered Salcomine in a fluid, either the air from which 
oxygen is being absorbed, or some inert fluid such as 
an oil, and circulating the suspension through the 
cooled absorption zone and the heated desorption 
zone. This kind of operation possesses several ad¬ 
vantages over the stationary packed bed. The output 
of oxygen is continuous, thus making it unnecessary 
to have several units operating on staggered cycles 
and greatly simplifying the problem of control. The 
major part of the heat load is eliminated, as only the 
powder is heated and cooled, and the problem of heat 
transfer to the absorbent is simplified because of the 
intimate contact between the powder and the heating 
and cooling media. 


Suspension in Air 30 

An experimental study was made of the fluidized 
system, in which the powder was suspended in air 
during absorption and in heated, recirculated oxygen 
during desorption. 

While this system appears simple, it was found to 
be impractical from the standpoint of ease of opera¬ 
tion, reliability, and portability. Estimates indicate 
that a unit of this type would weigh more than a 
stationary bed unit of the same oxygen capacity. In 
the light of subsequent experience it is also probable 
that it would be difficult to operate a fluidized cycle 
in such a way as to avoid rapid deterioration of the 
chelate. 

11 - 8 - 2 Salcomine-in-Oil System 31 - 32 ’ 33 

The investigation of the process of oxygen pro¬ 
duction by means of a circulating suspension of Sal¬ 
comine in a refined white oil was carried out on a 
semi-plant scale. The oil used was a highly refined 
hydrocarbon oil containing only saturated paraffins 
and saturated naphthenic constituents. The Salco¬ 
mine was suspended in the oil by ball milling, the 
suspension containing about 25% solids. 

The apparatus consisted of a stirred autoclave, in 
which the Salcomine suspension was treated with air 
at about 20 C and 150 psi. The suspension flowed 
from the autoclave into a separator where residual 
air and nitrogen was removed at 10 to 25 in. Hg 
vacuum through a heater into a desorbing tower, and 
then through a cooler from which a pump returned 
it to the autoclave. The rate of production of oxygen 
in this system was about 50 to 60 cu ft per hr. 

The useful life of Salcomine under these conditions 
is only about 150 hr, corresponding to about 300 
cycles. This is a very unsatisfactory life in compari¬ 
son with that which can be realized in a properly 
designed packed bed unit. 

11 8 3 “Circulating Solid” System 43 

In this system, for which experimental apparatus 
was built and tested, the absorbent such as Salcomine 
or methomine in powder form is circulated by means 
of a screw conveyor, first through a chamber in 
which absorption conditions prevail, and then 
through a second chamber in which desorption 
conditions prevail. The reactant may therefore be 
circulated cyclically, passing the powder reactant 
through gas-tight locks. Many of the advantages of 
“fluidized” operation should be possible. 



258 


OXYGEN GENERATION FROM REGENERATIVE CHEMICALS 


11.8 4 Adiabatic and Semi-adiabatic 
Operation 30 

The immediate advantage of adiabatic operation is 
that the heat of reaction of Salcomine and oxygen 
is stored in the compound and becomes available for 
desorption. In this way the overall heat load is sub¬ 
stantially reduced. In semi-adiabatic operation, the 
heat furnished by an absorbing bed is used to heat a 
bed undergoing desorption, the system as a whole 
being adiabatic. 

Several disadvantages in such systems are at once 
apparent. In order to produce a temperature in the 
oxygenated bed sufficient for rapid desorption, the 
temperature must be allowed to rise to such a degree 
that considerable pressure must be applied during 
absorption to overcome the considerable back pres¬ 
sure of oxygen over the hot, oxygenated bed; or 
else a smaller amount of absorption must he ac¬ 
cepted. For this reason the amount of absorbent and 
the reactor weight would be large. The oxygen pur¬ 
ity would be low since pumping out inerts before 
desorption would reduce the yield of oxygen consid¬ 
erably because of the '‘flashing'’ off of oxygen from 
the hot bed upon release of pressure. The high 
temperature level during absorption and desorption 
would be expected to reduce the useful life of the 
absorbent. 

Since the life of Ethomine was found to be very 
short under the conditions of adiabatic operation it 
was believed that a compound (or mixture) having 
a lower operating temperature would be more stable. 
In Table 9 is given the total production of various 


Table 9. Total production of various mixed chelates. 


Compound 

Operating temperature 

Life* 

Ethomine 

90 C 

7 

Ethomine-Salcomine 1 :1 

30 C 

3 

Methomine-Ethomine 3 :1 

50 C 

9 

Methomine-Ethomine 1 :1 

60 C 

10 


*Total production, lb 0 2 per lb compound, operating at 250 psi 
absorption, 0.1 atm desorption, circulating fluid semi-adiabatic unit. 


mixed chelates. It is apparent that there is no regu¬ 
lar relationship between life and optimum operating 
temperature, and that the total productive capacity 
of any of the substances tested under these condi¬ 
tions is quite low. 

It was concluded that the semi-adiabatic system 
would make an ideal field unit if a suitably stable 
compound were available. Fluomine might be such 
a compound but it has not been tested under these 
conditions. 


n.s.s Packed Beds in Heat Exchangers 

The 5 / 2-in. Tube Unit 23 

The results of studies of the fluidized and adiabatic 
systems led to the conclusion that the most effective 
method of operation of Salcomine-like compounds 
would prove to be in a system operating as follow’s. 

1. Absorption under superatmospheric pressure, 
with a cooling fluid to carry away the heat of reaction 
and to maintain the lied at a suitable absorption tem¬ 
perature. 

2. Desorption under atmospheric or reduced pres¬ 
sure, with a heating fluid to supply the heat of re¬ 
action. 

The important operating variables for this kind of 
operation are (1) the time of the absorption and de¬ 
sorption periods, (2) the temperature of the cooling 
water, (3) the air pressure used, (4) the tempera¬ 
ture of the heating fluid. (5) the pressure of desorp¬ 
tion, (6) the quality (humidity, cleanliness, et cetera) 
of the air used, and (7) miscellaneous factors, such 
as the kind of chelate, its history, pellet size, and 
hardness. 

The J/ 2 -in. tube unit is shown in Figure 12. Air 
was cleaned, filtered, and dried (if desired), and the 
temperature of the steam used for desorption was 
controlled by suitable throttling. The standard test 
weight of absorbent used was 42.5 g. and an air rate 


SILICA GEL 



Figure 12. General piping diagram of y 2 -wch unit. 

























METHODS OF OPERATION OF THE CYCLE 


259 


of 3 cfh per tube was used as standard for most of 
the tests. Automatic control of the cycle was pro¬ 
vided by a timer which operated the water-actuated 
piston valves. In later modifications of this appa¬ 
ratus bellows-operated valves were adopted as most 
satisfactory. 

The oxygen evolved upon desorption was collected 
over water in a calibrated burette. Desorption could 
be carried out under vacuum or at atmospheric pres¬ 
sure. 

Two terms will be used to denote the activity of 
the compound being considered. Productivity (P) 
is a term which refers to the actual amount of oxy¬ 
gen produced under cycling conditions. It is de¬ 
pendent upon the actual cycle and the conditions of 
absorption and desorption. By integration of a plot 
of productivity vs the number of cycles, the total 
amount of oxygen produced by a unit at any time 
may be determined. Saturation ( S ) is the total 
activity of the compound at any time and is a measure 
of the amount of compound present which is capable 
of absorbing oxygen. For Salcomine, saturation is 
the amount of oxygen absorbed in 1 hr at 25 C, when 
the agent is exposed to 1 atm of oxygen or its equiva¬ 
lent in air pressure. For Ethomine, saturation is the 
amount of oxygen absorbed in 1 hr at 25 C under 
1-atm pressure of air. 

Deterioration is usually expressed as per cent of 
original saturation, although the term production de¬ 
terioration can be used to refer to the loss in pro¬ 
ductivity. In general, the loss in saturation does not 
correspond exactly to the loss in productivity, the 
latter being somewhat greater. 

In Figure 13 are shown the results of a number of 
life tests on Salcomine in the p 2 -in. tube unit. The 
cycles used in these runs were derived from a stand¬ 
ard cycle by changing one or occasionally two vari¬ 
ables (such as absorption pressure, desorption pres¬ 
sure, cooling and heating fluid temperatures). 

In Figure 14 are replotted the results of those 
runs which differ only in the desorption conditions 
and in the moisture content of the air used for ab¬ 
sorption. The marked effect of low-pressure de¬ 
sorption is at once apparent. Changing the desorp¬ 
tion pressure changes the equilibrium temperature at 
which oxygen is evolved, and if constant heating 
fluid temperature is maintained, the available tem¬ 
perature difference for supplying the heat of desorp¬ 
tion is increased as the desorption pressure is low¬ 
ered. This results in an increased desorption rate and 
thus it is possible to choose cycle times which will 


permit a minimum time of exposure of the chelate 
to high-temperature oxygen. 

Referring to run A123 (Figure 13) in which a 
high (130 C) desorption temperature was used, it 
can be seen that deterioration is quite rapid. Deteri¬ 
oration brought about by exposure to oxygen at ele¬ 
vated temperatures is called “cooking” deterioration, 
and may be considered as the kind of oxidation that 
might go on when any organic substance is exposed 
to pure oxygen at an elevated temperature. 

Experiments were conducted to study this cooking 
deterioration separately. Samples of Ethomine and 
of Salcomine were held at constant temperature in 
an air or oxygen atmosphere and periodically tested 
for activity. In Figure 15 are shown results for 
samples maintained in a desorbed condition. 

On the basis of the experimental observations dis¬ 
cussed above, it is possible to select cycle conditions 
in which all the factors contributing to long life and 
high production can be made to exert their maxi¬ 
mum effect. “Ideal” cycles using the Ri-in. tube unit 
were selected for Ethomine and for Salcomine. The 
results of life tests using the ideal cycle for Salco¬ 
mine are shown graphically in Figure 16. It is seen 
that in this cycle 41 lb of oxygen are produced per 
lb of chelate to 50% of original saturation. 

In Figure 17 are shown life curves for Fluomine, 
Ethomine, and Salcomine, the data having been ob¬ 
tained in tests using the Y>-in. tube unit. 21 The 
markedly superior stability of Fluomine is evident. 

118 6 Proposed Reactors for Use in 
Aircraft Wing Units 

In connection with the design of a proposed air¬ 
craft wing unit for the production of oxygen in flight, 
using Salcomine or one of its derivatives, consider¬ 
able study was devoted to the selection of an efficient, 
lightweight reactor. A tube bundle proved to have 
good performance characteristics, but considerable 
difficulty was anticipated in fabrication of such units. 
Units of this kind containing different sized tubes 
were compared. It was found that a ^ 2 -in. tube 
bundle would produce 1.3 times as much oxygen for 
the same weight of chemical as would the Y -in. tube 
bundle. When very thin tubes (0.020-in. wall) were 
used, the ^4-in. tube bundle would produce 1.17 
times as much oxygen as would the in. tube bundle 
for a given weight of chemical plus tubes. 

A finned reactor of novel design (Figure 18), built 
by the Frigidaire Division of the General Motors 
Corporation, Dayton, Ohio, is superior to the tube 




260 


OXYGEN GENERATION FROM REGENERATIVE CHEMICALS 




0 -1-1—2-s--3 

0 500 1000 1500 

CYCLES 


UNIT A69-40LB ABSORPTION 






UNIT AII9 CHARCOAL AND SODA 



UNIT AI23- 130° 
DESORPTION 




UNIT AI2I-WET AIR-0.75 ATM 
DESORPTION 



UNIT A80-0.33 ATM DESORPTION UNIT AI22- 8°C COOLING 





UNIT AI09-0.I0 ATM DESORPTION 



Figure 13. Results of a number of life tests on Salcomine. 






































METHODS OF OPERATION OF THE CYCLE 


261 


bundle in space requirements (0.080 cu ft per lb of 
absorbent as compared with 0.115 cu ft per lb), and 
equal to the tube bundle in performance in cyclical 
oxygen production. 



TOTAL OXYGEN PRODUCED (LBS/LB SALCOMINE) 


A, A: I ATM DESORPTION (AII9.AII6) 

B, B: 0.75 ATM DESORPTION (A 120, A121 ) 

C, C': 0.33 ATM DESORPTION ( A 80, A 108) 
D: O.IO ATM DESORPTION (A 109) 


Figure 14. Salcomine life as a function of desorption 
pressure. 


< 

(E 

O 


O 

<r 

o 



O ETH0MINE-02-I ATM 
® ETHOMINE-0 2 -4.4 ATM 
A SALC0MINE-0 2 -l ATM 

® SALC0MINE-0 Z -| ATM-WET (DEW POINT IOC) 
V ETH0MINE-0 2 - I ATM-WET (DEW POINT IOC) 
o ETHOMINE —AIR-1 ATM 


Figure 15. Deterioration of desorbed Ethomine and 
Salcomine at constant temperature and oxygen partial 
pressure. 




lbs/o 2 produced/lb compound 

Figure 17. Life curves for Fluomine, Ethomine, and 
Salcomine. 


11. 8 . 7 Reactors Using Fins, Coils, et cetera, 
for Heat Transfer Surface 

A variety of reactor designs were devised and 
tested during various phases of the developmental 
work. Of these the most suitable, and the one adopted 
for application to a prototype unit, is the so-called 
flat case. 35 

The flat case consists of four layers of 8 copper 
tubes each, horizontally disposed, ^-in. OD by 24 in. 
long, spaced in. on centers. Square fins (1 $4 in¬ 
square) of 0.012-in. sheet aluminum are placed six 
to the inch along the length of each tube. The total 
surface is 100 sq ft in contact with the absorbent 
(2.78 sq ft per lb of Salcomine). Figure 19 shows 
the experimental flat case, and Figure 20 shows the 
reactor (without the shell) designed for the ship¬ 
board unit (see below), embodying the flat-case ele¬ 
ment. 

In an earlier experimental unit (Kellogg-Ameri- 
can Machine Defense Shipboard Unit), 41 ’ 49 four re¬ 
actor cases were provided, each with a heat transfer 
surface made from % 6 -in. copper tubing wound in 
24 flat spiral coils and spaced about % 6 i n - apart at 
nearest approach. The total heat transfer surface 
is 134 sq ft; each case holds 160 lb of absorbent. 
About 30 cu ft of oxygen could be absorbed in 5 
min, the rate of heat absorption thus being 32,500 
Btu per hr. 

11 8 8 Operating Characteristics of the 
Shallow Bed Reactor 35 

Air Supply Variables 

In general, the highest air pressure economically 
available should be used during absorption. This 
statement is subject to the following qualifications: 


Figure 16. Salcomine life on improved cycle. 














262 


OXYGEN GENERATION FROM REGENERATIVE CHEMICALS 



Figure 18. Aircraft unit reactor. 


(1) the pressuring and depressuring of a case results 
in a mechanical disintegration of the particles of ab¬ 
sorbent, and the use of excessively high-pressure air 
would result in excessive powdering of the granules, 

(2) the weights of metal required to withstand high 
pressures may become very large, increasing the 
heating and cooling load to some degree, (3) the loss 


of air on blowing down a case under high pressure 
is considerable. 

The effect of air pressure as the only variable upon 
the absorption rates of Salcomine is shown in Fig¬ 
ure 21. It can he seen that the absorption rate in¬ 
creases with increasing pressure, but it also appears 
that the rate of increase drops off at 110 psi, and that 







































METHODS OF OPERATION OF THE CYCLE 263 



Figure 19. Experimental flat case. 


no economical advantage is to be gained by going to 
higher pressures. 

A study of the effect of air rate upon the absorp¬ 
tion rate of Salcomine has shown that no appreciable 
increase in rate is obtained by increasing the air rate 
above 0.42 cu ft per min per lb of absorbent. 

Air Quality. The effect of air quality (humidity, 
oiliness, temperature) has been investigated, chiefly 
in connection with life tests. The quality of the air 
has no observable effect upon the operating charac¬ 
teristics of Salcomine over a short time interval, its 
chief effect being on chelate life in continued opera¬ 
tion. 

Cooling Water. The cooling water temperature is 
an important engineering variable. Its effect has 
been studied, and it has been found that at low air 
rates (0.2 cu ft per min per lb) no marked effect 
is observed on raising the cooling water temperature 
above 50 F until about 90 F is approached. At high 
air rates (0.4 cu ft per min per lb) a marked diminu¬ 
tion in yield is observed before 90 F is reached. 

Heating Fluid. The desorption conditions, and 


particularly the temperature of the heating fluid, are 
of great importance both in the production of Salco¬ 
mine per cycle and in its life in service. 

During desorption, heat transfer is definitely the 
controlling variable so far as the rate of desorption 
is concerned. The use of a high temperature heating 
fluid is desirable because of the increased rate of heat 
transfer into the bed, the temperature of a desorbing 
particle being dependent only upon its oxygen con¬ 
tent and the partial pressure of oxygen to which it 
is exposed. 

The use of excessively hot heating fluids must be 
avoided, however, for two reasons. The most impor¬ 
tant of these is that the deterioration of Salcomine 
and its congeners is due partly to exposure to high 
temperatures in the presence of oxygen. Although 
the temperature of the desorbing chelate is not ma¬ 
terially dependent upon the heating fluid temperature, 
after a given particle is desorbed it can reach the 
temperature of the heating fluid and thus undergo 
cooking deterioration. 

The importance of using low desorption pressures 






264 


OXYGEN GENERATION FROM REGENERATIVE CHEMICALS 



' 


f m " v ' 




Figure 20. Reactor designed for shipboard unit. Shell removed. 


has been pointed out in the discussion of the j/ 2 -in. 
tube tests. With a low desorption pressure, it is 
possible to use either a lower temperature heating 
fluid or a shorter desorption period (with a higher 
temperature fluid). Both of these conditions are 
favorable to long chelate life. 

Chelate Life in Shallow Bed Reactors. It has al¬ 
ready been shown that the life of chelate compounds 
of the Salcomine type is markedly influenced by the 
cycle conditions, and particularly by the desorption 
conditions. 

The results of some studies on the effect of air 
quality and desorption pressure upon the deteriora¬ 
tion of Salcomine in the “flat case” are given in 
Table 10. 

118 9 The Shipboard Unit 43 ’ 46 ’ 47 

Arthur D. Little, Incorporated, and E. B. Badger 
and Sons Company were commissioned to design and 
build a unit on the basis of performance data ob¬ 


tained using a high productivity cycle with the high 
heat transfer shallow bed. 

Table 10. Effect of air quality and desorption pressure 
upon the deterioration of Salcomine. 

Per cent loss in activity per 10 lb 
0 2 produced per lb 

Desorption pressure Saturation Production 



Dry air* 

Wet air 

Dry air 

Wet air 

0.33 atm 

11.0 

7.3 

11.7 

9.6 

0.50 atm 

11.6 

8.8 

11.4 

9.7 

1 .0 atm 

13.8 

25.0 

10.0 

17.5 


* Dry air, SO C dew point; wet air. 13 C dew point. 


The reactor design was based upon the shallow 
bed heat transfer element and a design worked out 
earlier by E. B. Badger and Sons Company for use 
on another unit. It consists of a finned element hold¬ 
ing 120 lb of Salcomine granules, enclosed in a tubu¬ 
lar steel shell. A view of the inner element, with the 

































DETERIORATION OF SALCOMINE, ET CETERA, IN CYCLIC OPERATION 


265 



Figure 21. Effect of air pressure as the only variable 
upon the absorption rates of Salcomine. 


top plate removed, is shown in Figure 20, and a com¬ 
plete flow diagram of the unit is shown in Figure 22. b 

11 9 DETERIORATION OF SALCO¬ 
MINE, ET CETERA, IN 
CYCLIC OPER¬ 
ATION 

The conclusions which have been reached in re¬ 
gard to chelate deterioration as a result of all the 
studies 35 (chemical and cycling tests) can he sum¬ 
marized as follows. 

1. The deterioration of Salcomine and Ethomine 
in cyclic operation occurs by two distinct processes: 


b This unit was installed on a Naval repair vessel in 
1943, 14 when unexpected operation in tropical waters re¬ 
quired the addition of a refrigerated air cooler. Later, 
corrosion necessitated replacement of the reactor tubes. Un¬ 
der the severe conditions of operation, the deterioration of 
the Salcomine was greater than experienced in laboratory 
tests so that only about A]/ 2 lb of oxygen were obtained per 
lb of Salcomine used; this introduced a problem of supply 
and recharging. In spite of these difficulties the Commanding 
Officer of the USS Prairie stated, “It is believed that the 
unit is an excellent one and when the mechanical difficulties 
are overcome will be an excellent addition to any ship. 


one is associated with the production of oxygen (pro¬ 
duction), and the other with the contact of the chelate 
with a hot oxygen atmosphere (cooking). 

2. These two processes of degradation are similar 
with respect to the final changes involved hut are 
distinct with respect to mechanism. 

3. Deterioration by the cooking reaction is a func¬ 
tion of the desorption pressure and temperature. The 
oxygen partial pressure is involved to the 0.7 to 0.8 
power for Ethomine and to the 0.4 power for Salco¬ 
mine. Water vapor has no effect upon this reaction. 
A detailed mechanism of the cooking reaction has 
not been proposed, hut it is supposed that the Schiff’s 
base linkages are the labile points of attack. 

4. The chemical deterioration associated with oxy¬ 
gen production is influenced only slightly by the de¬ 
sorption conditions, and appears to be the inescapable 
price that must he paid for oxygen production. It 
has been suggested that the maintenance of low tem¬ 
peratures during absorption will prevent the occur¬ 
rence of added deterioration of this sort over what 
invariably accompanies the release of oxygen from 
the oxygenated complex. 

5. Desorption at low pressures affords a consider¬ 
able improvement in the ratio of saturation loss to 
chemical deterioration. In the ideal case this ratio 
is, of course, unity; and the observed ratio for 0.1 
atm desorption approaches this ideal value. 

6. The mechanism of the production deterioration 
reaction is not known with certainty, but it has been 
supposed to simulate a molecular rearrangement of 
the activated, oxygenated complex, in which the oxy¬ 
gen, instead of being released, attacks the Schiff’s 
base linkage of the chelate. The direct loss of carbon 
as CO or C0 2 is apparently not a result of the pri¬ 
mary step of this process. For Salcomine there ap¬ 
pears to he no loss of the integral chelate atoms 
except for hydrogen, which is probably lost in fur¬ 
ther oxidative attack upon the primarily degraded 
molecule. Water vapor in the desorption atmosphere 
has only a slight catalytic influence upon the rate of 
chemical deterioration, but increases the saturation 
loss threefold. 

7. The discovery of effective production-deterio¬ 
ration inhibitors seems unlikely, but an inhibitor for 
the cooking reaction may he found. It is probable 
that the great stability of Fluomine is due to its re¬ 
sistance to both types of deterioration reactions. 

8. Methods of reactivating deteriorated chelate in 
situ have not been discovered, hut it has been shown 
that chemically intact material can be removed by 







266 


OXYGEN GENERATION FROM REGENERATIVE CHEMICALS 


TO OXYGEN 
STORAGE 


LEGENO 

A AIR 
8 BLOWDOWN 
E EXHAUST 
0 OXYGEN 
S STEAM 
V VACUUM 
FW FRESH WATER 
SW SEA WATER 

INLET SIDE OF BELLOWS VALVES 
INDICATED BY SHADED FLANGE 



TIMER 

MANIFOLD 


Figure 22. Flow diagram of shipboard oxygen unit. 






































































































































































































































































































































































































TOXICITY OF SALCOMINE DUSTS 


267 


solvent extraction and reactivated separately. Re¬ 
covery of salicylaldehyde (or the substituted alde¬ 
hyde from Ethomine, etc.) and cobalt from the de¬ 
teriorated chelate is readily accomplished by acid 
hydrolysis. 

9. For long chelate life, low desorption pressures 
and temperatures and good heat transfer during ab¬ 
sorption are essential. 

11 10 TOXICITY OF SALCOMINE 
DUSTS 

It was early noted in working with Salcomine 
and related compounds that the dust is very irritat¬ 
ing to the bronchial passages and to the digestive 
system. This prompted an investigation of the pos¬ 
sible industrial hazards which might be involved in 
working with this compound. 0 Preliminary testing 
revealed that Salcomine dust is toxic upon inhalation 
or ingestion. Mice exposed for several hours to the 
dust frequently died within one to six days and 
autopsies revealed many pathological changes attrib¬ 
uted to the Salcomine. The functions of the liver 

c Animal studies were made with Salcomine at the toxi¬ 
cological laboratory at the University of Chicago under the 
auspices of Division 9, of NDRC, and are reported in the 
summary report for Division 9 under the heading Miscellane¬ 
ous Toxicological Studies. 


appeared to be especially affected. Similar results 
were obtained with larger animals such as rats, 
guinea pigs, and rabbits. 36 ’ 37 

Examinations made of eleven men 38 exposed to 
small amounts of Salcomine dust revealed that the 
compound produces irritation of the eyes, nose, 
larynx, and bronchial tubes. The symptoms which 
appeared shortly after exposure and resembled those 
of an upper respiratory infection, cleared up a short 
time after removal from exposure. Signs possibly 
indicative of mild systemic affects (muscular aches, 
nausea, and vomiting) appeared in some of the sub¬ 
jects after a latency of 5 to 24 hr. 

One case with much more severe systemic affects 
has been reported. 39 Exposure for a short period 
with an atmosphere laden with Salcomine dust led 
to inflammation of the liver, which became progres¬ 
sively more enlarged. The liver condition and the 
accompanying jaundice gradually improved but ab¬ 
dominal pains still persisted. Two months later an 
abscess of the liver was discovered and removed. It 
was suspected that other abscesses were also pres¬ 
ent. A second similar abscess was removed three 
months later. Recovery was slow. 

It is probable that the use of dust masks and 
general precautions taken against dust will effective¬ 
ly guard against Salcomine as an industrial hazard. 




Chapter 12 

OXYGEN GENERATION FROM NON- 
REGENERATIVE CHEMICALS 

By S. S. Prentiss a 


121 INTRODUCTION 

A survey was made of inorganic chemical sources 
of oxygen that would he suitable for emergency 
supplies of oxygen in the field, and which also might 
be better adapted than the compressed gas cylinders 
normally available to specialized uses such as medical 
therapy, and cutting and welding for small isolated 
and infrequent jobs. The more obvious materials are 
listed in Table l; 3 a number of other materials and 
methods have been omitted because they are less 
suitable from the point of view of weight per cent 
yield of oxygen, or the character of the reaction. 

Prime consideration was given to yield of oxygen 
on a weight and volume basis, and also to availability. 
The cost of the materials was generally of secondary 
or minor importance, as the contemplated uses were 
all of an emergency character. 

Two chemical sources of oxygen were outstanding 
because of the availability of the materials and nature 
of the reactions involved. These are (1) alkali per¬ 
oxides, especially sodium peroxide and potassium 
tetroxide, which liberate relatively pure oxygen when 
treated with water or moist air, and (2) alkali chlor¬ 
ates, especially potassium chlorate and sodium 
chlorate, which liberate oxygen when heated. The 
Naval Research Laboratory did much work in the 
development of these materials as sources of oxygen 
prior to and during the NDRC program. 

The peroxides permit generation on a demand basis 
from simple apparatus, but do require large quantities 
of water. Reaction with moist air, not only to gen¬ 
erate oxygen but also to absorb carbon dioxide and 
water vapor, makes possible the most economical 
source of breathing oxygen known, the rebreather. 
The development of such generators and rebreathers 
will he discussed in the following sections. 

The alkali chlorates require no water, produce 
pure, dry oxygen from apparatus of low weight and 
great density. Generators of this type are quick-start¬ 
ing over a wide range of temperature and are adapt¬ 
able to aviation use. Modified forms of apparatus 
for therapeutic oxygen, cutting, welding, et cetera, 

"Technical Aide, Division 11, NDRC. 


w r ere contemplated but never developed. The de¬ 
velopment of aircraft emergency equipment is dis¬ 
cussed in a subsequent section. It should be noted 
that the chlorates and perchlorates of the polyvalent 
metals such as magnesium, zinc, and aluminum are 
reduced to simple oxides with liberation of part of 
the oxygen and all of the chlorine; they are, there¬ 
fore, unsuited to oxygen generation. 

A word can be said about several of the materials 
in Table 1. Hydrogen peroxide decomposes very 
smoothly and in many ways would be an ideal source 
of oxygen; however, it is not practical on a weight 
basis unless high concentrations (90%) can be uti¬ 
lized. In high concentration, there is some hazard in 
storage and transportation, especially in metal con¬ 
tainers. Large-quantity production of high concen¬ 
tration hydrogen peroxide has recently been devel¬ 
oped^ and container problems may some day be 
satisfactorily solved to maintain the weight-saving 
inherent in the peroxide itself. 

An examination of several reversible processes 
(for example, the Brin process using barium perox¬ 
ide, and the Tessie du Motay process using alkali 
permanganates) led to the conclusion that they were 
not competitive with other portable methods of pro¬ 
ducing 500 to 1,000 cu ft of oxygen per hr on the 
basis of weight of equipment and fuel required, and 
certainly they were not suitable for small-scale, 
emergency generators. 

12 2 OXYGEN GENERATORS EMPLOY¬ 
ING ALKALI PEROXIDES 

12 2 1 Chemistry of the Peroxides 

Sodium peroxide is formed by the oxidation of 
metallic sodium in a dry atmosphere of oxygen or 
air. On treatment with water, decomposition takes 
place according to the following reaction. 

Na 2 0 2 -f H 2 0 2NaOH + 40 2 . (1) 

The heat of reaction is 73.2 calories per gram-mole 
of oxygen produced. 

b See STR Division 11, Volume 2. 


268 




OXYGEN GENERATORS EMPLOYING ALKALI PEROXIDES 269 


Table 1. 

Inorganic chemical sources of oxygen. 





Heat of 




Per cent Cu ft 0 2 

Reac- 

• 

Chemical 

Mol 

o 2 

per lb 

tion 

Remarks 


Wt 

Yield 

(20 C) 

Cal per 






Mole 0 2 

Lithium peroxide Li 2 0 2 

46.0 

35.0 



Not available, but offers for production have 






been made 

Lithium tetroxide Li 2 0 4 

78.0 

61.5 



Not available (unknown?) 

Sodium hydrogen peroxide Na(OOH) 

56.0 

28.5 



Not available 

Sodium peroxide Na 2 0 2 

78.0 

20.5 

2.40 

73.2 

Available in large quantities 

Potassium peroxide K 2 0 2 

110.2 

14.5 



Intermediate stage in formation of K 2 0 4 

Potassium tetroxide K 2 0 4 

142.2 

33.6 

3.94 

17.5 

Recently available in quantity 

Hydrogen peroxide H 2 0 2 (100 vol) 

34.0 

13.2 

1.54 

45.8 

Commercial grade 

Hydrogen peroxide H 2 O 2 (130 vol) 

34.0 

16.5 

1.93 

45.8 

Most concentrated grade made commercially 

Hydrogen peroxide H 2 0 2 (300 vol) 

34.0 

42.5 

4.97 

45.8 

90% H 2 0 2 ; generally considered hazardous to 






ship and store, only recently available in quan- 

Magnesium peroxide Mg0 2 

56.3 

28.4 

3.32 


tity 

Not available 

Calcium peroxide Ca0 2 

72.0 

22.0 

2.60 


Commercial product generally 80% pure 

Calcium tetroxide CaO-i 

104.0 

46.1 



Ca0 2 containing up to 9% Ca0 4 reported 

Calacium hydrogen peroxide Ca(OOH) 2 

106.0 

30.2 




Ca0 2 2H 2 0 2 

140.0 

34.2 




Calcium hypochlorite Ca(C10) 2 4H 2 O 

215.1 

14.9 



A laboratory method 

Strontium peroxide Sr0 2 

119.6 

13.4 




Sr0 2 2H 2 0 2 

153.6 

31.2 




Barium peroxide Ba0 2 

169.4 

9.45 

1.10 


Brin process; regenerate with air 

Barium hydrogen peroxide Ba(OOH) 2 

203.4 

15.8 




NaB0 :i H 2 0 2 

100.0 

16.0 

1.87 

(40-50) 


Na 2 B 4 0 ; 4H 2 0 2 

325 

19 

2.22 

(40-50) 


Na 2 C0 3 1.5H 2 0 2 

157 

15 

1.75 



Sodium chlorate NaClOs 

106.5 

45 

5.28 


Available in large quantities; decomposable by 






heat 

Sodium chlorate candle 


34.5 

4.03 


Combustion yielding pure oxygen 

Sodium perchlorate NaClCh 

122.5 

52 

6.10 


Not available in large quantity 

Potassium chlorate KC10 3 

122.6 

39.1 

3.35 



Potassium chlorate candle 


25.2 

2.94 


Superseded by NaClCh compositions 

Potassium perchlorate KClO-i 

138.6 

46 

5.38 


Not available in large quantity 

Table 2. 

Available 

oxygen 

from alkali peroxides. 






Amount re- 



Theoretical 

covered in Heat of Heat of 

Peroxide 

Theoretical 

0 2 yield 

0 2 Recovery actual prac- reaction reaction 


0 2 yield (cu ft per lb) in 

actual tice(cuft (kg cal per (Btupercu 


(Wt %) 

STP 

practice (%) per lb) STP mole 0 2 ) ft) STP 

Sodium peroxide (Na 2 0 2 ) 

20. 

5 

2.32 


97 2.24 73.2 367 

Mixed peroxide (54% Na 2 0 2 —46% K 2 0 4 ) 

26. 

8 

3.0 


89 2.27 48.1 238 

Potassium tetroxide (K 2 0 4 ) 

34 


3.81 


96 3.65 17.5 88 


Potassium tetroxide is formed by oxidation of 
metallic potassium in an atmosphere of dry air. This 
material decomposes with water according to the 
following equation: 

K 2 0 4 + HoO -» 2KOH + 1 y 2 0 2 . (2) 

The heat of reaction is 17.5 calories per gram-mole 
of oxygen. 

A mixture of sodium peroxide and potassium 
tetroxide containing potassium and sodium in the 
molar ration of 46 to 54 may be formed from burn¬ 


ing an alloy obtained by heating and distilling a 
mixture of metallic sodium and potassium chloride. 
The yield and heat of reaction is intermediate to that 
for the pure substances. The yield of oxygen produc¬ 
tion from these materials is given in Table 2. The 
above reactions between water and sodium peroxide 
or potassium tetroxide proceed readily and smoothly 
at temperatures somewhat in excess of room temper¬ 
atures, but when cold w r ater is used the reaction at 
best is very sluggish and it is necessary to supply a 
catalyst. One of the simplest forms of such a catalyst 















270 


OXYGEN FROM NON-REGENERATIVE CHEMICALS 


is a trace of copper sulfate, which may be added 
to the water supply. 

12 2 2 Generating Devices 

A generator operating on the Kipp principle was 
developed. In this generator a large outer container 
is partially filled with water. Located in this con¬ 
tainer is a second container in which alkali peroxide 
is placed. A center perforated tube in the inner con¬ 
tainer connects with the water in the bottom and 
operates in such a fashion that withdrawal of the 
generated oxygen from the inner container permits 


In order to prepare oxygen gas for breathing 
purposes, the generated product is scrubbed with 
water, first in the main body of water in the gen¬ 
erator and then in an auxiliary scrubber located on 
the outside of the container. Cooling coils and a trap 
serve to remove water condensed at ambient temper¬ 
ature. A second regulator serves to deliver the 
oxygen at a desired pressure up to the pressure of 
generation. Figure 1 shows the general arrangement 
and operation of the generator. Figure 2 illustrates 
several systems which were investigated. 1 

Sufficient water is provided in the generator to 



entrance of water to the mass of peroxide. A solu¬ 
tion of caustic which is formed as a by-product drains 
through this same tube to the main body of water in 
the generator. The generated oxygen issues through 
a pressure controlled regulator so that a constant 
pressure is maintained in the generator throughout 
the operation. 


absorb the heat of reaction so that the boiling point 
is not quite reached at the end of the charge. It will 
be observed from Table 2 that approximately 4 times 
as much heat is liberated per mole of oxygen gen¬ 
erated in the case of sodium peroxide than in the 
case of potassium tetroxide. For this reason a gener¬ 
ator designed to operate with sodium peroxide must 

































































































































OXYGEN GENERATORS EMPLOYING ALKALI PEROXIDES 


271 


be considerably larger to accommodate the excess of 
water required for absorbing this heat of reaction. 
The water required to absorb the heat of reaction is 
many times that required in the chemical reaction 
itself. 

The first generator developed produces 10 cu ft of 
oxygen per charge and operates automatically at any 
set pressure from 1 to 22 psi and at any rate de¬ 
manded up to 100 cfh. The outer container has a 


and enclosing these elements in a protecting steel 
cover. This apparatus was designed for use as a 
field unit for therapeutic administration of oxygen 
to twenty patients. 2 An oxygen-distributing hose is 
provided with constant flow fittings and masks. 
Each station (patient) is provided with two outlet 
openings of different flow rates, and the flow rate 
from the system as a whole can be varied by varying 
the delivery pressure to the hose. 


TO GAS METER 


F 




I 

E—A 


WATER 

TANK 


TO GAS METER 



WATER 

HEAD 

TANK 


TANK 


REGULATING VALVE 

/—- 

f f -V '(- 

_I L —, TO GAS 

METER 


1 


N , A -4 DISTRIBUTOR 
+ | PLATE 


I iLl 

IQ 

I 

• o 

I cr 
I ^ 


=. w I 


< I 
m i 


"V 

SCREEN 


TO GAS METER 



SMALL BELL TYPE BELL TYPE WATER SPRAY TYPE CENTER TUBE TYPE 

Figure 2. Generator types investigated for use with alkali peroxides. 


volume of 42 gal and is filled with 29 gal of water. 
Forty-five pounds of sodium peroxide are placed in 
the inner container. A second generator of smaller 
size was built for an emergency welding unit capable 
of producing 22 cu ft of oxygen from a 10-lb charge 
of sodium peroxide c (see Figure 3). The operation 
and general arrangement of the apparatus is similar 
to that described above. 

A further modification provided a heavy walled 
vessel and suitable regulators to provide an operating 
pressure of 100 psi for underwater cutting opera¬ 
tions. This unit has a capacity of 100 cu ft of gas 
per charge. The appearance is similar to the model 
shown in Figure 3. 

A still further modification comprised some slight 
alterations permissible when K 2 0 4 is used as the 
agent, namely, a reduction in the amount of water 
required and an increase in capacity of the peroxide 
chamber. This model has a capacity of 300 cu ft of 
oxygen per charge of peroxide and was further modi¬ 
fied to provide ruggedness in the field by mounting 
all valves, scrubbers, etc., on the top of the container 

c The experimental investigation was conducted and the 
model made by the du Pont Company, Electrochemicals 
Department. Production models and approximately 4,000 
units were produced by the Sight-Feed Generator Company. 


12 2 3 Rebreather Unit for Aircraft Use 

Introduction 

The most economical source of breathing oxygen 
for high-altitude aircraft use is the closed-circuit re¬ 
breather system in which oxygen is supplied and 
carbon dioxide and moisture are removed in com¬ 
pliance with the physiological requirements. Non¬ 
rebreathing systems, in widespread use, are uneco¬ 
nomical to the extent that gas must be delivered each 
minute to the lungs in an amount equal to the respira¬ 
tory minute volume used. Even the most efficient 
non-rebreather system, in which the oxygen is diluted 
to an optimum degree with ambient air, requires up 
to 5 times as much oxygen as the rebreather system 
over the important altitude range from 15,000 to 
35,000 ft. 

In spite of the fundamental economy, rebreather 
systems have suffered from liabilities which have 
proved so serious in practice that their use in avia¬ 
tion practically disappeared. 4 

A consideration of some of the difficulties with 
earlier rebreather systems, and the attempts made to 
solve some of their deficiencies will show that these 
systems, for the most part, have been too complex 



























































































272 


OXYGEN FROM NON-REGENERATIVE CHEMICALS 




Figure 3. Oxygen generator—22 cu ft model. 









































































































































































OXYGEN GENERATORS EMPLOYING ALKALI PEROXIDES 


273 


and too unreliable for aircraft use, especially under 
emergency conditions. 

Simple rebreathers using alkali peroxides date 
back to 1904. 5 In these and later rebreathers, sodium 
peroxide is used as the source of oxygen through 
reaction with moisture and carbon dioxide of the 
expired breath. Under the conditions of use, the 
oxygen was never liberated at a rate sufficient to 
supply the requirements of the user nor to give a 
margin of safety over small leaks in the system. 
Early workers recognized the advantage of potassium 
tetroxide over sodium peroxide in giving higher 
yields and rates of oxygen evolution, but it has not 
been until recent years that potassium tetroxide or 
the so-called mixed oxides of sodium and potassium 
(represented by NaK0 3 ) have been commercially 
available. Therefore, in these early forms of re¬ 
breather apparatus, it has been necessary to furnish 
an auxiliary supply of oxygen, for example, com¬ 
pressed gas, to meet this deficiency. 

The recycled gas in the system may become di¬ 
luted with inert gases, such as nitrogen, from the 
atmosphere through leaks or slow evolution of nitro¬ 
gen from the back of tissues, and thus require purg¬ 
ing by means of automatic small volume pumps and 
auxiliary supplies of oxygen. 6 

Any rebreather system which is to be used in avi¬ 
ation, especially if it may be required in emergency 
at “oxygen” altitude, must have an initial filling of 
oxygen and also sufficient liberation of heat to warm 
the chemical to a reactive temperature. Several 
attempts 5 * * ’ 7,8,9 ’ 10 have been made to improve on the 
Navy rebreather (electrically heated) in this respect. 6 

In the method to be described, a small chlorate 
candle embedded in the canister of potassium tetrox¬ 
ide gives off both oxygen and heat when ignited at 
time of use. 

An improved rebreather unit known as C-K 10 
was developed to take full advantage of potassium 
tetroxide and to provide an inherently simple system 


6 The C-K oxygen unit is a direct outgrowth of the simpli¬ 

fied rebreather planned and tested by Goldschmidt and 

Chambers, the Laboratory of Physiology, University of 

Pennsylvania Medical School, and constructed by Rawson 

in 1944. Further, it combines elements of potassium tetroxide, 
suitably catalyzed and granulated for rebreathers, as de¬ 
veloped by P. Borgstrom and his associates at the Naval 
Research Laboratory, and of chlorate candles (described 
later in this chapter). Contributions to the development of 
these candles were made by the British Admiralty, the 
Naval Research Laboratory, the Oldbury Chemical Com¬ 
pany, and others. 


which might be stored indefinitely and used under 
emergency conditions and at altitudes up to 35,000 
ft at ambient temperatures down to —50 C. e 

Description of C-K Rebreather Unit 

The C-K rebreather consists of a canister loaded 
with granular potassium tetroxide in which are em¬ 
bedded three chlorate candle primers with a firing 
mechanism. To the bottom of the canister is at¬ 
tached a flexible breathing bag protected by a fabric 
casing. Means are provided at the top of the canister 
for connecting a standard demand-type oxygen mask 
provided with a loaded expiratory valve (see Figure 
4). The entire unit, with the exception of the mask 



Figure 4. Principle of operation of C-K oxygen re¬ 
breather unit. 


and connecting tubing, is hermetically sealed and 
compactly packaged for transportation and storage. 
For emergency use, a rip cord is pulled, thereby 
breaking the seals on the canister, freeing the breath¬ 
ing bag, igniting one chlorate candle primer, and 
disclosing the mask connection. Ignition of the 
chlorate candle provides oxygen to fill the breathing 
bag initially and supply breathing requirements for 
the first few minutes, and heat to warm the potassium 
tetroxide to operating temperature. 

* Experimental units were developed by the Johnson 
Foundation under contract OEMcmr-26. Production models 
were developed and constructed in lots for experimental 
testing under Contract OEMsr-934. “C-K” or Candle-KOX 
is a code abbreviation used during development. 
















274 


OXYGEN FROM NON-REGENERATIVE CHEMICALS 


The five principal components of the device are 
described in the paragraphs which follow. 

1. The face piece, with loaded expiratory valve, 
and associated tubing. 

2. The canister proper, containing the potassium 
tetroxide (KOX) and housing the chlorate candle 
primers. 

3. The candle primers with their associated 
ignition and filter mechanisms. 

4. The breathing bag. 

5. External fittings to provide thermal insulation, 
mechanical protection, and means of support. 



used, 2y 2 in. thick, A l / 2 in. wide, and 5 y 2 in. high. 
The canister contains about 300 g of the pressed and 
catalyzed potassium tetroxide (KOX) screened so 
that all particles are between 2 and 4 mesh in size. 1 
The total oxygen capacity is about 200 ml of oxy¬ 
gen per g. With full utilization of the oxygen ob¬ 
tainable from the KOX, the canister should last an 
average man at rest for about 180 to 200 min. Due 
to the extra oxygen liberated by the chemical (which 
serves the necessary function of keeping the system 
flushed with fresh gas) the actual canister life is 
only about half this. 



UNLOADED LOADED 

Figure 5. Sectional view of the Legallais optionally loaded expiratory valve. The device consists basically of a metal 
diaphragm so upset at its center as to have only two positions of stability, and a mechanism for changing it from one 
position to the other. In the “unloaded” position, the diaphragm is completely free of the mushroom valve and does not 
interfere in any way with its normal operation. In the “loaded” position, the diaphragm presses against the rim of the 
rubber mushroom valve, giving restricted opening. 


The Face Piece, Valve, and Tubing. The unit is 
designed to be used in conjunction with the standard 
Army and Navy A-14 oxygen mask, or any other 
mask with the same connector and expiratory valve. 

Use of the C-K unit requires the mask expiratory 
valve to be loaded to at least 5 cm of water; the load¬ 
ing on the regular A-14 mask valve is from 2 to 5 
mm of water; if the mask is to be used interchange¬ 
ably with the demand system and with the C-K unit, 
its expiratory valve must therefore he replaced by one 
having optional loading. Legallais has designed such 
a valve which is illustrated in Figure 5. It behaves 
exactly like a standard valve until the front of the 
mask is pressed in. which transforms it into a loaded 
valve. To release the loading, the mask is squeezed 
laterally. 

Canister. A standard MSA gas mask canister is 


A schematic section of the C-K unit (CK6 series 
as made at the Johnson Foundation) is given in 
Figure 6. The top carries the female connector for 
the oxygen mask, a simple check valve which keeps 
the system from losing excessive oxygen when the 
mask is not plugged in. supports for the three chlorate 
candle primers, and supporting structures for the 
starting and opening devices described below. In the 
new version with grenade fuse ignition, the canister 
top also carries the trigger mechanisms and percus¬ 
sion caps. The canister bottom is provided with a 
thin metal foil seal, which is punctured by a special 
perforator at the moment the unit is put in operation. 
It also supports an oval ring on which the breathing 
bag is bound. Screen and Fiberglas filters at top and 
bottom together with a spring evading device are 
provided to keep the KOX in place. 

























































OXYGEN GENERATORS EMPLOYING ALKALI PEROXIDES 


TOP CANISTER SEAL RUBBER STOPPER 


TO FIT STANOARD OXYGEN MASK CONNECTOR 


COMBINED CHECK VALVE 
AND SAFETY VALVE 


BALING STRAP CLIP 
HOLDER 


FIBERGLASS FILTER 
8 SCREEN FILTER 
SUPPORT 


CLI P 



BALL HANDLE 


INITIAL STARTING LEVER 


TRIGGER WIRE FOR INITIAL CANDLE 
PRIMER 


RESERVE STARTING LEVER 

RESERVE RING HANOLE 


COIL SPRING DRIVER FOR 
CANDLE STRIKER 

CANDLE STRIKER 

RED PHOSPHORUS CANDLE 
STRIKER 


MSA UNIVERSAL CANISTER 
RESERVE CANDLE PRIMER 


FIBERGLASS CLOTH 
INSULATING COVER 


BALOON CLOTH OUTER GUARD 


FIBER GLASS FILTER AND 
SCREEN FILTER SUPPORT 


PERFORATOR FOR BRASS 
FOIL SEAL 


COPPER CANDLE HOLDER 
l ST STAGE IGNITOR (BLACK) 

Uf) 

2 STAGE IGNITOR (RED) 

CHLORATE CANDLE (GRAY) 

CRYSTALLINE COPPER SULFATE 
(THERMAL PROTECTION FOR CANDLE FILTER) 

CANDLE FILTER "AA" FIBERGLASS 
MAT 

COPPER SCREEN FILTER SUPPORT 


BALING STRAP 


SPRING DRIVE FOR 
PERFORATOR 


RELEASE VANES FOR 
PERFORATOR 


002 BRASS FOIL SEAL 
(PERFORATED) 


THREE LITER BREATHING BAG 
HORCO RUBBER SHEETING 


275 


Figure 6. Schematic section of C-K oxygen rebreather unit. 















































































































































































276 


OXYGEN FROM NON-REGENERATIVE CHEMICALS 


The Chlorate Candle Primers. The three primers 
are identical, though one serves to start the unit in 
operation, and the other two act as reserves. Each 
consists of an outer copper case, an igniter, a chlorate 
candle, and a smoke filter. The form developed at 
the Johnson Foundation and supplied in the early 
sample units distributed to the Services uses a 
phosphorus igniter. In later units this igniter was 
replaced by the simpler and more reliable grenade 
fuze igniter developed for this purpose by the Cat¬ 
alyst Research Corporation. Since there are consid¬ 
erable differences between the two forms, both will 
be briefly described. They are functionally identical, 
except that the new form starts liberating its oxygen 
a little more quickly than does the old one. 

In the older form, igniter and candle are housed 
in a flat box made of 0.010-in. copper sheet, enclos¬ 
ing a pressed candle of the same shape. The striker 
mechanism (Figure 7) is contained in a cylindrical 
projection at the top end of the box. It consists of 
a striker disk on which red phosphorus is glued, and 
which is screwed on to a stationary thread stud. 
When a piano wire trigger is pulled out by the 
starting lever or reserve levers, the striker disk 
spins down onto the candle and ignites it. The open 
end of the candle box is covered with two layers of 
Fiberglas AA mat held in place with screen and 
baling wire. This filter effectively removes the 
particles of sodium chloride liberated by the burn¬ 
ing candle, unless its temperature rises above 150 C. 
To keep the filter temperature below this value some 
copper sulphate crystals (CuS0 4 • 5IFO) are placed 
between the candle and the filter; these absorb heat. 
The new form utilizing a modified grenade fuze 
igniter is mechanically simpler. The mechanical part 
of the igniter, a spring-driven hammer, is mounted 
on top of the canister instead of within it. The ham¬ 
mer strikes a conventional copper primer cap set flush 
in the canister top. From it a small brass tube 
extends inside the canister to the tubular copper 
spinning which serves as the candleholder. The 
tube contains a suitable quantity of flash mixture, set 
off by the primer cap and in turn igniting the 
cylindrical cast candle. The candle is 1 in. in diameter 
and about 2 in. long and weighs about 50 g. A layer 
of Hopcalite takes over the heat-absorbing function 
of the copper sulfate in the older form, and two 
layers of Fiberglas A A mat again act as a smoke 
filter. The entire primer assembly is held together 
by rolling the edge of the copper candleholder over 
the flared end of the flash tube, and the contents are 


kept firmly in place by a small compression coil 
spring. 

Figure 8 gives the rate of oxygen evolution by 
candle primer with phosphorous ignition at an am¬ 
bient temperature of —40 C. In later forms, the 
characteristics are much the same except that initial 



Figure 7. Phosphorous ignition mechanism for chlorate 
candle. 


evolution is at its maximum rate so that 2 liters are 
produced in the first 20 seconds, instead of 1 liter in 
the first minute. The rate of oxygen evolution by 
the candle is about 30% higher when the ambient 
temperature is 25 C instead of —10 C. 

Breathing Bag. The 3-liter breathing bag is at¬ 
tached directly to the bottom of the canister. The 






































































































OXYGEN GENERATORS EMPLOYING ALKALI PEROXIDES 


277 


bag is made of rubber sheeting, identical to that used 
in the diaphragms of Pioneer demand regulators 
(Horco No. 2796). Mechanical protection is pro¬ 
vided by an outer covering of balloon cloth. Both 
bags are of simple wedge shape, slightly larger at 
the bottom than at the neck. 



Figure 8. Rate of oxygen evolution by candle primer 
in C-K oxygen rebreather unit. 


Since the bag openings are of the same area as the 
canister bottom, it is practically impossible to kink 
them in such a way as to prevent free entrance and 
exit of air (see Figure 9). In the packaged condi¬ 
tion, the breathing bag is folded flat against the side 
of the canister where it occupies very little space. 

Scaling and Starting Mechanisms. Potassium 
tetroxide and sodium chlorate change their proper¬ 
ties when exposed to moisture. It was therefore of 
the utmost importance that the inside of the canister 
containing these chemicals be hermetically sealed 
against the atmosphere. They must, however, be in¬ 
stantly available for use with a minimum of handling. 
Seals had to be provided, therefore, at the top and 
bottom of the canister which would be tight but 
quickly breakable. For NDRC laboratory-made 
samples, the top seal has been merely a rubber 
stopper fastened directly to the starting level, which 
is pulled free when the starting ball is pulled (Figure 
6). This was replaced on production samples by a 
crimped bottle cap to be positively thrown off by 
the starting lever as it is pulled away. The seal be¬ 
tween the canister bottom and the breathing bag 


consists of a disk of 0.002-in. brass soldered across 
a hole in the canister bottom, and perforated by a 
simple metal guillotine driven by a mouse-trap spring, 
and released when the folded bag springs away from 
the canister bottom, as a result of the pulling of the 
starting ball (see Figure 6). 



Figure 9. C-K oxygen rebreather unit worn by a kneel¬ 
ing subject showing operation of reserve ring. Though 
the bag appears to be caught under the canister bottom 
it has such a wide mouth that the passage of air is not 
obstructed in any way. 

The candle primers are ignited in the laboratory- 
built samples by pulling the piano wire triggers 
through the soft solder seals in the canister top. 
Fastened to their outer ends, these wires have small 
balls which engage with slots on the operating 
levers, so that the first candle is automatically ignited 
when the ball is pulled, while each of the reserves is 
ignited when its corresponding reserve ring is pulled 
free of the unit. 

External Fittings. The metal canister is surround¬ 
ed by two layers of medium-weight Fiberglas cloth 
as thermal insulation for the unit and for the flier. 
The outer cloth bag is extended up over the entire 










OXYGEN FROM NON-REGENERATIVE CHEMICALS 


278 


canister to provide a neat covering, and is held in 
place by a simple baling strap harness which also is 
the anchorage for the clothes clip. A small Micarta 
bag guard covers the folded bag, and also hides the 
two reserve rings so that there will be no possibility 
of their being pulled until tbe unit is in operation. 

Operation of the C-K Unit 

The C-K unit is designed to be useful as an emer¬ 
gency or stand-by system for aircraft using the pres¬ 
ent diluter-demand oxygen installations. To serve 
this purpose it must withstand storage without de¬ 
terioration and rough handling without damage, but 
must be instantly ready for use, and capable of being 
put into operation with a minimum amount of ma¬ 
nipulation. When the starting ball at the top of the 
unit is pulled free, six actions follow automatically: 
(1) the top canister seal is broken by tearing off the 
bottle cap, (2) the connector for the mask tube is 
thereby freed, (3) the hammer of the initial candle 
primer is released to strike its percussion cap, thereby 
igniting this candle, (4) the bag guard is forced away 
from the canister, revealing the two reserve rings, 

(5) this also frees the breathing bag, which unfolds, 

(6) the perforator for the lower canister seal is re¬ 
leased and punctures the foil which separates canister 
from breathing bag. 

The initial primer starts to liberate oxygen at once, 
and should provide enough for a normal inspiration 
(500 ml) in 15 sec, which is little longer than the 
time required to transfer the mask from another sys¬ 
tem to the C-K unit. A check valve in the canister 
top prevents undue wastage of oxygen, if the mask is 
not immediately connected. 

Shortly after the unit is connected, the mask ex¬ 
piratory valve must be loaded to about 5 cm of water 
or more. If a Legallais valve (Figure 5) is used in 
an A-14 mask, this is accomplished by merely press¬ 
ing tbe front of the mask. 

During the next two minutes, oxygen will be fed 
into the system at a rate of about 5 liters per minute 
STPD. f Heat is also liberated by tbe primer during 
these 2 minutes, so that by tbe time the candle has 
burned out, enough of the KOX should be warmed 
to a reactive temperature to take over tbe load of 
furnishing oxygen. There is thus a shift from a fixed 
flow emergency blast system of low economy and 
liberal safety margin to a chemical demand system 
of high economy and reduced safety factor. 


Warning of Canister Exhaustion. A distinctive 
feature of the C-K unit is its method of warning the 
wearer that the canister is nearing the end of its use¬ 
ful life. Potassium superoxide, when used in this 
breathing apparatus, possesses the property of losing 
its oxygen-generating power before it has lost its 
capacity to absorb carbon dioxide. After Xf/i to 2 hr 
of use, when the unit is near exhaustion, the expired 
carbon dioxide continues to be absorbed, but is not 
replaced by oxygen, and as a result the sensation of 
“striking bottom,” or bag collapse at the end of in¬ 
spiration, gives positive but progressive warning. 

By the mere pull of a reserve ring, a second 
primer is at once brought into action and fills the bag. 
This reserve candle, like the initial one, keeps the bag 
full and overflowing for about 3 minutes, after which 
the bag begins to empty once more, reaching collapse 
about 10 minutes after tbe ring has been pulled. The 
second reserve primer can then be brought into play, 
if it has not already been used for another purpose. 

It should be emphasized that the ability of the ab¬ 
sorbing power of KOX to outlast its generating 
power, on which the warning system depends, is not 
automatically guaranteed by the use of KOX. How¬ 
ever, in seven experiments in which bag collapse 
occurred while oximeter readings were being taken, 
the saturation was 92% or higher at the moment the 
warning was given. In at least six other instances, 
bottoming of the bag has occurred due to exhaustion 
of the chemical, and though saturation records were 
not taken, there were no subjective symptoms of 
anoxia. 

Margin of Safety. Tbe C-K unit has been designed 
for altitudes up to 35,000 ft and for temperatures 
down to —45 C, and it has been given tests under 
these conditions in the decompression chamber. The 
safety factor should be a little greater than that for 
the standard diluter-demand systems since the oxy¬ 
gen fraction of inspired gas is close to 1.00 instead of 
being adjusted to some figure between 0.21 and 1.00, 
depending on tbe altitude. The percentage leak 
caused by a hole of given size will be somewhat 
smaller for the unit than for a demand system, be¬ 
cause while the pressure drop through the canister 
is about the same as that through the standard 6-ft 
tube used with the demand regulator (see Figure 10), 
the suction required to empty the breathing bag is 
somewhat less than that required to initiate flow 
from the regulator. The self-flushing feature of the 
unit has a greater margin of safety at altitude than at 
sea level. 


r STPD, standard temperature and pressure dry. 






OXYGEN GENERATORS EMPLOYING ALKALI PEROXIDES 


279 


The system could easily be converted to a safety 
pressure one by merely introducing a spring con¬ 
straint in the breathing bag which always tended to 
empty it. The liability of such a system would be 
that small outboard leaks would tend to empty the 
bag and give the “collapsed bag” warning before the 
canister was really exhausted, thus reducing the ef¬ 
fective life of the unit. A very low safety pressure 
loading might, however, prove a more satisfactory 
solution than the present unloaded form. 



Figure 10. Flow resistance of C-K canister before and 
after use. Pressure drop from canister bottom to face, 
using A-14 mask. 


Economy. The economies of a number of different 
oxygen systems are compared in Figures 11 and 12. 
It can be seen at once that no gaseous system begins 
to approach the economy of the C-K unit, whether 
calculated on a weight or on a volume basis. If the 
standard oxygen installation on a B-17 were replaced 
by enough C-K units to provide an equivalent oxygen 
supply (5 units per man), the total weight would be 
cut from 480 to 160 lb, a saving of 320 lb. 

Possible Uses 

The device was designed for use in aviation. Three 
uses have been suggested in this field. 

1. As an emergency and walkabout system for 
planes equipped with regular demand systems (B-17, 
B-24, etc.). 

2. As the sole oxygen system for planes with nor¬ 
mally pressurized cabins (for example, B-29), to be 
used as a stand-by system in case of loss of pressur¬ 
ization. 

3. As the sole oxygen supply for airplanes nor¬ 
mally operating below oxygen altitudes, but which 
may be required to make occasional missions at 
higher altitudes, and in which there is no regular 


oxygen installation, for example, many B-25s, B-26s; 
perhaps some air transport operations. 

Suggested Further Development. The features of 
the unit which adapt it to emergency conditions in 
the air also fit it for emergency use in mines, ships, 



Figure 11. Weight storage efficiencies of various oxygen 
systems. 



VOLUME OCCUPIED BY EQUIPMENT-CU FT 
( LOGARITHMIC SCALE) 

Figure 12. Volume storage efficiencies of various oxygen 
systems. 










280 


OXYGEN FROM NON-REGENERATIVE CHEMICALS 


and gas-filled buildings. It could be used in its pres¬ 
ent form as a self-rescue unit, but for this purpose 
would be improved by providing a small mask or 
mouthpiece as an integral part, omitting the two re¬ 
serve candles, increasing the bag size, and reducing 
the canister size to provide a somewhat shorter useful 
life. It is not adapted for sustained heavy work espe¬ 
cially in warm locations, such as would be required 
of rescue crews, because of inadequate provision for 
heat dissipation and because of small canister size. 
Preliminary work has indicated that such a self¬ 
rescue unit will weigh (with mouthpiece) about 2 lb, 
measure 2x4x7 in., and have a duration of about 
half an hour. 

Satisfaction of Physiological Requirements 

Uniform Conditions. In any system making use of 
alkali peroxides, liberation of oxygen and the absorp¬ 
tion of carbon dioxide are linked together: 

2K0 2 -|- C0 2 —» K 2 C0 3 + 12 O 0 . (3) 

If this were the only reaction to be considered, the 
picture would be simple: for each mole of C0 2 ab¬ 
sorbed, 1% moles of oxygen are generated. How¬ 
ever, the situation is not as simple as this, for alkali 
peroxides also react with water, again liberating 1 1 / 2 
moles of oxygen per mole of absorbed substances: 

2K0 2 + H 2 0 -» 2KOH 4 - 140o. (4) 

The hydroxide formed is available for the neu¬ 
tralization of more C0 2 , without accompanying pro¬ 
duction of oxygen. 

In view of these theoretical complications, recourse 
was had to empirical tests of overall behavior. In a 
series of experiments at simulated altitudes ranging 
from 20,000 to 35,000 ft in the altitude chamber, the 
adequacy of the C-K unit to supply oxygen was 
checked by means of continuous gas sampling from 
the mask, utilizing a Pauling oxygen meter g or a Lilly 
nitrogen meter , 15 or by continuous measurement of 
oxygen saturation with an oximeter. The minimum 
recorded saturation in five experiments was 87%. 
The total time spent above 20.000 ft in these five 
experiments was about 380 min. 

There is ample evidence for the efficacy of KOX as 
a carbon dioxide absorbent in respiratory apparatus 
whose configuration is much less favorable than in 
the present device . 12 ’ 13 

Resistance to gas flow through the canister depends 


8 See Chapter 14. 


upon the geometry of the system and the caking of 
chemical within it. The matter was carefully studied 
at the National Institute of Health . 13 In a number 
of tests of the experimental C-K units, it has given 
no trouble whatever. Two such tests on a single can¬ 
ister are plotted in Figure 10. The lack of clogging 
is not an indication of incomplete reaction of the 
chemical, since analysis of the canister material after 
use has shown that from 85% to 90% of the available 
oxygen has been liberated. 

Transient Conditions. Two types of transient con¬ 
ditions are critical for rebreather systems: suddenly 
increasing activity and suddenly decreasing altitude. 
By the use of a large 3-liter breathing bag, and by 
keeping the KOX always in a warm and therefore 
highly reactive condition, there is provided a margin 
which has shown itself adequate to deal with bursts 
of sudden activity alternated with periods of rest. 

In a sudden descent from altitude, the gas in the 
closed system is compressed to a smaller volume, and 
again there is danger that the bag will collapse com¬ 
pletely before the deficiency is made up by the excess 
of gas liberated over the amount absorbed. The 3- 
liter bag was tested in the following way: after the 
unit had been in use at 30.000 ft and at —30 C for 
about one hour, the chamber was suddenly dived to 
20,000 ft at a rate of 10,000 ft per min. The bag 
almost collapsed at the end of inspiration as the lower 
altitude was reached, but quickly filled up again. If 
the dive bad been much faster, or had gone to a still 
lower altitude, it would have been necessary to pull 
one of the reserve rings to preserve conditions of 
normal respiration. 

A third type of transient condition, though an arti¬ 
ficial one, provided an even more stringent test of the 
device; this was the sudden replacement of oxygen 
by air in the bag and lungs while the unit was in 
operation at altitude. The record of an experiment in 
which this was deliberately performed is plotted in 
Figure 13. Simultaneous measurements were taken 
of arterial oxygen saturation and of the nitrogen 
fraction of the gas in the mask. The altitude was 
30,000 ft, the temperature 0 C, and the subject had 
been breathing on the unit for about one hour. At 
a signal, the mask was disconnected from the can¬ 
ister and the breathing bag was squeezed flat to empty 
it of gas. The subject then took several breaths of 
air, inspired deeply, and reconnected his mask to the 
unit. As can he seen from Figure 13, the arterial 
saturation dropped from 93 to 87 % during the half 
minute in which air was breathed, remained at about 




SODIUM CHLORATE CANDLE APPARATUS FOR AIRCRAFT 


281 


that level for the next half minute, and then rapidly 
rose so that within 90 seconds after reconnecting the 
mask the blood saturation was above the original 
value. The figures for concentration of nitrogen in 
the mask follow a corresponding course. 



TIME - SECONDS 

Figure 13. Recovery of subject using C-K oxygen re¬ 
breather unit after collapse of bag. 

Conclusions 

The tests here reported were obtained with labora¬ 
tory models; units of a production model for evalua¬ 
tion by the Army Air Force and the Navy Bureau 
of Aeronautics were not available in time for in¬ 
clusion in this report. 

Our conclusion from the tests is that the C-K unit 
is adequate for both ordinary and emergency oxygen 
needs at altitudes up to 35,000 ft and at temperatures 
down to —45 C. With light activity at room tem¬ 
perature, the gas inspired from the canister becomes 
warm, but not uncomfortably so. Under conditions 
of sustained heavy work, such as is required of ship 
rescue parties, however, the inspired gas becomes 
unpleasantly hot and the canister gets too hot to hold 
in the bare hands. Over the range of temperatures 
usual in military aircraft at altitudes, the warmth of 
this inspired gas should be an asset rather than a 
liability. 


12 3 SODIUM CHLORATE CANDLE 
APPARATUS FOR AIRCRAFT USE 

12 3 1 Introduction 

Although the decomposition of potassium chlorate 
was first described in 1785, 16 relatively little is known 


concerning its mechanism. Mellor 17 suggests depict¬ 
ing the reaction as follows: 


or 


6KCIO3 


370 C 
-» 


370 C 

v 


KC1 + 3KC10, + 80 kcal, 
500 C 


'.2KC1 -f- 30o + 28 kcal 3KC1 + 6CL — 24 kcal. 

( 5 ) 

Little is known concerning the relative rates of re¬ 
action at different temperatures. 18 ’ 19 The decomposi¬ 
tion of both chlorate and perchlorate is catalyzed by 
various metallic oxides, including Mn0 2 , CuO, 
Fe 2 0 3 , Co 2 0 3 , Ni 2 0 3 , and oxides of vanadium, 
uranium, and tungsten. 17 The rate of decomposition 
of KClCh as a function of temperature and concentra¬ 
tion of catalyst has been studied by Otto and Fry, 20 
who found that the reaction rate is increased about 
1.6-fold for each 10 C rise in temperature. For any 
given reaction rate, relatively large concentrations 
of Fe 2 0 3 are required to reduce the reaction tem¬ 
perature substantially. 

The oxygen candle apparatus [OCA] employing 
sodium chlorate is a compact, portable source of oxy¬ 
gen designed to supply personnel in military aircraft 
for periods of 30 to 40 min. There are two major 
uses for which the apparatus is intended: (1) gen¬ 
eral purpose walk-around and emergency oxygen 
supply in aircraft equipped with standard demand 
oxygen systems, and (2) occasional or emergency use 
in aircraft which ordinarily require no permanent 
oxygen installations, such as in pressurized cabin 
aircraft, medium altitude bombers, and transport 
planes. Figures 11 and 12 show the weight and vol¬ 
ume storage efficiencies of standard aviation oxygen 
cylinders now in use by the Services. Various ex¬ 
perimental units and chemicals, including the OCA, 
are shown for comparison. In contrast to cylinder 
oxygen, the storage efficiency of liquid or chemical 
oxygen is relatively high, particularly in the weight 
and volume range of portable units. 

The use of chlorate candle oxygen generators for 
this purpose was suggested by developments already 
under way at the Naval Research Laboratory for ap¬ 
plication in submarines. Sodium chlorate was imme¬ 
diately available in ton lots at a low cost. It there¬ 
fore appeared possible to provide oxygen economi¬ 
cally in expendable units which would require no 
servicing and which could be shipped, stored, and 
used in much the same way as tinned food. 

The development of such an oxygen system for air¬ 
craft use was started late in 1943. It proceeded as a 










282 


OXYGEN FROM NON-REGENERATIVE CHEMICALS 


joint project among several laboratories. The Naval 
Research Laboratory and the Oldbury Electro¬ 
chemical Company were concerned chiefly with the 
development of the candle. The Mine Safety Appli¬ 
ances Company, under contract with Division 11 of 
NDRC, worked on production problems and on the 
development of a satisfactory ignition system. The 
Johnson Foundation, working under contract with 
the Committee on Medical Research, was concerned 
with physiological specifications, the design and test¬ 
ing of the apparatus, and practical aspects of the 
problem as it is related to military aircraft. 

The possibility of using chlorates as a source of 
commercial oxygen has been extensively investigated 
in Germany and numerous patents covering chlorate 
oxygen sources and methods of use were issued in 
Germany, France, and Japan prior to World War 
II. 21 In all these applications, the high temperature 
required for the decomposition of the chlorates and 
perchlorates is obtained in part from the heat of de¬ 
composition of the chlorate itself and in part from 
the oxidation of accessory combustible materials 
mixed with the chlorate. In 1930 Hoch 22 described 
an individual oxygen supply unit for use in mine 
rescue work which utilized oxygen from a chlorate 
“briquette” manufactured in Berlin under the trade 
name “Naszogen.” In 1933 the British Admiralty 
tested the German product as a possible means of 
oxygen replenishment in submarines, but the appara¬ 
tus was rejected because the oxygen liberated was 
contaminated with chlorine. 23 In 1942 the Japanese 
put into military service a chemical oxygen generator 
for aircraft use. 24 ’ 25 ’ 26 

Exploratory experiments with chlorate generators 
were made in England in 1942. The material tested 
at this time suffered from the same disadvantage as 
did the Japanese and German generators, that is, con¬ 
tamination of the oxygen with toxic impurities. 27 ’ 28 
At the request of the Naval Research Laboratory, 
the Oldbury Electrochemical Company of Niagara 
Falls, N.Y., undertook to improve the yield and 
purity of oxygen evolved from chlorates. The Old¬ 
bury Company arrived at the following formula: 


Sodium chlorate 

74% 

Powdered iron 

10 % 

Barium peroxide 

4% 

Fiberglas 

12 % 


This mixture represents a considerable improve¬ 
ment over previous chlorate generators. The substi¬ 
tution of NaC10 3 for KC10 3 increases the oxygen 


yield. The use of reduced Fe powder in place of 
carbon as an accessory heat source reduces contami¬ 
nation of the oxygen with CO and C0 2 although 
some CO is still formed from organic impurities in 
the mix (Table 3). The introduction of an alkaline 
oxidizing agent (4% BaCL) eliminates the formation 
of free chlorine. The technique devised by the Old¬ 
bury Company is as follows : 

The dry ingredients are mixed by stirring, moistened 
with 5 % by weight of water, and loaded into a rectangular 
mold measuring 9x1x1 in. Pressure of 5,000 psi is 
applied slowly along one side of the mold so as to compact 
the material transversely. After pressing, the mold is 
disassembled and the fragile cake dried at 100 C. After 
drying, the cake or “candle” has sufficient strength for 
handling. 

The Oldbury product was tested at the Naval Re¬ 
search Laboratory 28 and used in the first experi¬ 
mental models of the OCA in December 1943. The 
performance was sufficiently satisfactory to stimulate 
the investigation of methods for large-scale produc¬ 
tion. 29 The Mine Safety Appliances Company under¬ 
took to provide material for further experiment and 
to investigate the properties of the Oldbury product 
from the point of view of production. The molded 
candles manufactured by the MSA Company were 
of value to the experimental program but the proper¬ 
ties of the material varied greatly from one batch to 
the next and it soon became apparent that one or 
more unknown factors were present. The density 
of the molded candles may be varied from 1.9 g per 
cc to 2.2 g per cc by altering the pressure applied to 
the mold. However, variations in density appear to 
have little effect on the rate of evolution of oxygen. 
Increase in the quantity of water used in the initial 
mix decreased appreciably the rate of oxygen evolu¬ 
tion from the pressed and dried candle. 

Early in 1944 a new method of manufacture was 
introduced which avoided some of the variables com¬ 
plicating the production of uniform molded candles. 
The Naval Research Laboratory 30 explored the possi¬ 
bilities of fusing the dry mixture of ingredients and 
casting the molten material into blocks of the desired 
size and shape. The candles made by this method 
proved to be superior to any of the previous forms. 
The density, oxygen yield, strength, and uniformity 
were increased while the concentration of CO in the 
evolved oxygen was reduced to less than 0.01% (see 
Table 3). Furthermore, the method of manufacture 
proved to be more adaptable to mass production, and 
in December 1944 the manufacture of molded candles 
was discontinued in favor of the cast form. 






SODIUM CHLORATE CANDLE APPARATUS FOR AIRCRAFT 


283 


Table 3. Stages in the development of chlorate oxygen generators. 



German 
1930 trade- 

name 

“Naszogen” 

F rench 
molded 

Japanese 
in military 
service 
1941-42 
aircraft 

British 

I 1942 
molded 

Oldbury Co. 
for the 
NRL 
1942-13 
molded 

British 

II 1943 
molded 
(Trial ser¬ 
vice in sub¬ 
marines, 
1944) 

Naval Re¬ 
search Lab¬ 
oratory 
1944-45 
fused and 
cast 

% Compo¬ 
sition of 
generating 
compound 

0 2 source 

KCICh 

KCIO .3 

NaCIO, 


40 

40 

Ref 9 

Ref 10 

72.5 

74 

79 

80 

76 

75 

Supplemen¬ 
tary heat 
source 

C 

Fe 

10 

2 

0.4 ;: 

2.0 

.4* 

impurities 

12.5 

0.005* 

10 

Impurities 

5.5 

0 . 001 * 

10 

Binder 

Asbestos fiber 
Infusorial earth 
Silicious filler 
Fiberglas 


15 

3.9 

5.3 

12.1 

12 

12.6 

6 

Other 

ingredients 

(oxidizing 

agents, 

catalysts) 

Iron oxides 

Cu powder 

NiCos 

MnO* 

Ba0 2 


3 

15.6 

19.2 

0.6 

0.8 

0.1 

2.0 

4.0 

0.8 

0.1 

2.0 

4 

Density g/cc 



1.8 

1.8 

2.0 

1.7 

2.45 

Oxygen yield 

Weight per cent 
Vol 0 2 -Vol chem 
(liquid O. = 797) 



27.5 

350 

25.2* 

320* 

30.5 

430 

34.0* 

400 

34.1 

580 

Heat of reaction 

Cal/g material 
cal/liter 0 2 



210 * 

1 , 100 * 

250* 

1,420* 

215,226* 
1,060 

185* 

730 

201 , 200 * 

835 

Composition of 
evolved gas 

% o 2 

%C0 2 

%CI* 



96 *1 

3.5*1 

Present but 
adsorbed in 
filter 

.001 

99 

1 

0 


99.5 

.05 

0 

%co 



0.1 

.08 

.03 


.007 


* Calculated values. 


A summary of the composition and of certain 
properties of chlorate candles at various stages in 
their development is given in Table 3. 

12 .3.2 -phg Development of Sodium Chlorate 
Generators 

Properties of Chlorate Candles 

Description of Current Candle. The chlorate can¬ 
dle as it is produced for the OCA is a solid cylinder 
25.4 cm long and 4.1 cm in diameter (Figure 20). 
The candle weighs 810 to 815 g and displaces 330 cc 
(density = 2.45 0.05 g per cc). The interior is a 
gray, hard, homogeneous brittle material of about the 
same consistency as lava. The surface is green- 
brown, hard, and shiny. The melting point is 255 C 


and the material may be cast or recast from molten 
form to any convenient shape. It contains a dry mix¬ 
ture of the following ingredients : h 

NaClOs 81% 

Fe powder (reduced with hydrogen) 10% 

BaO a 3% 

Powdered Fiberglas (baked at 400 C) 6% 

One end of the candle contains a built-in ignition 
system which will he described in a subsequent sec¬ 
tion. After ignition the reaction continues uniformly 


h Throughout the remainder of this report, the candle com¬ 
positions are abbreviated to the form W — X — Y — Z. Where 
W = weight per cent NaClCb, X — %Fe, Y = %Ba0 2 , and 
Z — % glass. 


















































284 


OXYGEN FROM NON-REGENERATIVE CHEMICALS 


and is visible as a thin fluid layer of incandenscence 
which proceeds slowly down the cake, leaving a hot 
gray-black magnetic residue of fused salts, metallic 
oxides, and glass. 

Action of Iron. It might be expected that the pow¬ 
dered, reduced iron in the presence of 100% oxygen 
at high temperature would be completely oxidized: 

4Fe -f 30o 2Fe 2 0 3 381,000 cal 

(171 cal per g candle). (6) 

Of the oxygen available from tbe chlorate 12% would 
then be required to oxidize the iron and only 88% 
would be liberated as free oxygen. Actually this is 
not the case, for 95% of the oxygen contained in the 
chlorate is liberated (Figure 14). In the case of the 
cast candles, the oxygen yield may exceed the yield 
calculated on the assumption that all of the iron is 
converted to the lowest possible oxide and it must be 
concluded that one-third to one-half of the original 
iron is left uncombined with oxygen. As the con¬ 
centration of iron is increased, the proportion of iron 
oxidized is decreased (Figure 14). 


crams o 2 

PER GRAM 
CANDLE 



Figure 14. Oxidation of iron in cast candles. 


For candles of any given composition, the yield of 
oxygen appears to be independent of tbe burning 
rate. 

The conclusion that only a fraction of the iron is 
oxidized may be also derived from calorimetric meas¬ 


urements. Tbe heat of oxidation of iron to FeO, 
Fe 3 0 4 or Fe 2 0 3 is 4.0 kcal per g of combined oxygen. 
The ordinates of Figure 14 may, therefore, be ex¬ 
pressed directly in calories as indicated on the right- 
hand scale. 

Although the increase in total reaction heat caused 
by an increase in the concentration of iron is unex¬ 
pectedly small, it is ample to explain the change in 
decomposition rate. The specific heat of fused 
NaC10 3 is approximately 0.32 cal per g 31 so that, if 
the entire increment in heat of reaction were employed 
in raising the temperature of reaction, the change 
from 5 to 11 % iron would raise the temperature 
about 75 C. According to tbe data of Otto and Fry 20 
this should be sufficient to produce a 30-fold increase 
in the decomposition rate of KC10 4 . In practice the 
rate of decomposition is limited by other factors and 
the change from 5 to 11% Fe about doubles the rate 
of oxygen evolution as shown in Figure 15. For any 
given diameter there is a lower limit to the concentra¬ 
tion of iron at which the reaction will proceed reliably. 
For 1^-in. candles this limiting concentration is 
about 5% at room temperature. 



Figure 15. The effect of iron on the evolution of oxygen 
from cast candles at room temperature and constant 
barium peroxide concentration. 


Action of Barium Dioxide. Tbe BaOo was origi¬ 
nally introduced as a supplementary agent to elimi¬ 
nate free chlorine evolved from side reactions. 28 It 
was also observed that the addition of 1% BaOo in¬ 
creases the rate of oxygen evolution by 0.04 ± 0.006 
1 per min per cm 2 , an amount which is indistingmish- 
able from the effects of a similar change in the con- 





SODIUM CHLORATE CANDLE APPARATUS FOR AIRCRAFT 


285 


centration of iron. Figure 16 shows the relative 
effect of Ba0 2 and Fe on the maximum temperatures 
attained by thermocouple walls inserted into the 
candle. 



Figure 16. Effect of variation in the concentration of 
iron and barium peroxide upon the maximum tempera¬ 
ture of combustion (ambient temperature, 25 C). 


The concentration of glass may be varied from 6 
to 15% without appreciably affecting the burning rate 
of the chlorate candle. When the concentration is 
reduced below about 5% the cast candles tend to 
develop cracks during the cooling and hardening 
process. The glass used for the present candles is 
standard Owens-Corning “curly wool” Fiberglas. It 
is baked at 400 C before use in order to remove 
organic impurities, the incomplete oxidation of which 
leads to contamination of the oxygen with CO. 

Moisture. The candles are slightly hygroscopic 
and the rate of burning is slowed in candles contain¬ 
ing appreciable quantities of water. However, cast 
candles have been stored under room conditions in 
temperate climates for six months with the absorption 
of less than 1 g of water, and with no detectable 
change in oxygen yield or burning rate. Under con¬ 
ditions involving large changes of temperature and 
pressure, precautions against the absorption of water 
must be considered. 

Physical Factors Affecting the Rate of Oxygen 
Evolution. Factors affecting rate of oxygen evolu¬ 
tion are as follows. 

1. Heat conduction and burning rate. For candles 
of any given dimensions and composition the rate of 
oxygen evolution is determined by the temperature 
of the reactants immediately ahead of the burning 
front. Physical factors affecting the transmission of 
heat from the burned portion of the candle to the 
unburned portion may greatly alter the rate of oxygen 
flow. 


Figure 17 shows the effects of different conditions 
of insulation and heat conduction on the temperature 
of the unburned material below the incandescent 
front. In the experiment of curve I the conditions 
were such as to favor the transfer of heat from the 
hot residue to the unreacted portion. The candle was 
enclosed in a copper container, buried under six 
inches of insulating material (Vermiculite), and the 
hot oxygen allowed to pass over the unreacted chemi¬ 
cal. Under these conditions the temperature (as re¬ 
corded by Pt-10%Rh insulated thermocouples in¬ 
serted into the center of the candle) rose to the 
melting point 13.5 mm in advance of the incandescent 
front and the rate of oxygen evolution averaged 12 1 
per min STPD. In the experiment of curve III the 
candle was ignited in the open air; in this case the 
internal temperature did not rise to the melting point 
until the incandescent front was 5 mm distant, and 
the oxygen flow averaged only 5 1 per min STPD. 



Figure 17. Heat conduction in cast candles. 


2. Candle diameter and flow rate. It was found 
that the rate of oxygen production per unit area di¬ 
minishes slightly as the candle diameter is increased 
although the relation between flow rate and area is 
approximately linear in the experimental range. 36 
The maximum temperature reached by the residue 
increases slightly with diameter; presumably this 














286 


OXYGEN FROM NON-REGENERATIVE CHEMICALS 


results from a diminished surface to volume ratio 
available for heat loss. 

3. Low temperature. The performance of chlorate 
candles equilibrated with low temperatures is of par¬ 
ticular importance to their application in aviation. 
It was found that for l^-in. diameter candles in the 
range of temperatures —55 to 25 C, the change in 
oxygen production is about 0.02 1 per min per de¬ 
gree. Failures are likely to occur at —50 C among 
candles containing less than 9% Fe and 4% BaOo 
or when no insulation is provided. 

4. Absolute pressure. Under isothermal conditions 
the reaction rate is independent of absolute gas 
pressure over a wide range of values as shown in 
Figure 10. This is of practical importance in the 
design of equipment which is required to operate at 
altitude or where it is desired to use chlorate to refill 
oxygen cylinders under pressure. If the heat from the 
compressed oxygen is distributed to the unburned 
section of the candle, the rate of oxygen evolution 
may be greatly accelerated. 

5. Mechanical pressure and vibration. The candle 
substance is fluid at the site of reaction and the burned 
portion of the candle is easily separated from the un¬ 
burned portion, thereby interrupting the conduction 
of heat and stopping the reaction. The oxygen flow 
may be slowed in graded fashion by mechanical 
forces tending to separate the two ends of the candle; 
vibration (1200 cpm) or even slow shaking may 
greatly slow the reaction. Steady mechanical com¬ 
pression up to 10 psi between the two ends of the 
candle has little effect on the burning rate, although 
the candle may be “squashed” by such a procedure 
to four-fifths of its original length. 

Remarks on the Constancy of Flow. When candles 
of 1^-in. diameter are burned under conditions such 
that the mean flow rate exceeds 4.5 1 per min STPD, 
the variations in flow rate integrated over any one 
minute do not ordinarily exceed 0.5 1 per min. How¬ 
ever, there have been exceptions to this generaliza¬ 
tion, notably in candles of composition 81-10-3-6 
burned in tin containers, where the flow rate has 
fallen to one-half its rated value for periods of 30 to 
60 sec. 

The Ignition System 

The development of a simple method of igniting the 
generating compound which would operate reliably 
at —60 C and at altitude proved to be unexpectedly 
difficult. Much work was done in developing a three- 
stage ignition system in which the first stage was ig¬ 


nited by frictional contact with red phosphorus. This 
method had several deficiencies which were never 
satisfactorily remedied. The most serious of these— 
and also the most difficult problem to approach ex¬ 
perimentally—was its unreliability. At one stage in 
the work over 200 consecutive samples were ignited 
at —50 C without failure. This record of success 
was followed by a long series in which the number of 
failures ranged from 0 to 8 out of 10. There is little 
question that the problems involved in phosphorus 
ignition could eventually be solved, but the necessity 
for work along this line was obviated by the intro¬ 
duction, in November 1944, of a percussion igniter 
of the hand grenade type. The modified hand grenade 
bouchon (developed for the Mine Safety Appliances 
Company by the Catalyst Research Corporation) is 
available at low cost and the reliability of similar 
units used for munitions has already been proved on 
a large scale. 

The ignition system built around the grenade fuse 
is shown semi-diagrammaticallv in Figure 18. The 
ignition takes place in six stages as shown in the 
figure. The first three stages occur within the gre¬ 
nade and produce a flash which dissipates about 800 
cal in the course of 0.1 sec. 

A relative measure of the efficiency of energy 
transfer from the grenade to the candle primer may 
be made by determining the temperature of a copper 
disk of known weight inserted in place of the candle 
primer. Such a disk will absorb about 180 cal, indi¬ 
cating that the efficiency of transfer of energy is 
about 22% ; presumably the remaining heat is dissi¬ 
pated in the walls of the container. The transfer of 
heat by the grenade flame to the primer is markedly 
reduced at altitude. Primers which were reliably ig¬ 
nited at sea level occasionally failed at altitude and 
measurements with the copper disk technique showed 
that the energy transfer was reduced by about one- 
tbird at a pressure altitude of 50,000 ft. 

A series of 100 units of the configuration and com¬ 
position shown in Figure 18 has been run without 
failure at a pressure altitude of 50,000 ft and at —55 
C. The flow rates were measured in 15 cases and a 
statistical analysis of the results is shown in Figure 
19. The results appear to justify the belief that this 
form of ignition is reliable. However, experience 
with phosphorus ignition has shown that a statement 
of reliability cannot be made from 100 units. It 
should be noted that three out of six units failed to 
operate when the temperature was further reduced to 
—70 C. 



SODIUM CHLORATE CANDLE APPARATUS FOR AIRCRAFT 


287 


The total heat liberated by the ignition system is 
approximately 17 kcal (grenade fuse 0.8, primer 4, 
cast cone 12 kcal) in the course of one minute. This 
is in contrast to the candle proper, which liberates 
heat at the rate of about 4 kcal per min. This rapid 
evolution of heat from the igniter cones gives rise 
to two problems. 



Figure 18. The ignition system of modified hand-gren¬ 
ade bouchon. 

I. Percussion (hammer released by drawing cotter pin). 

II. Explosive mixture 35 KC10 4 , 30 Sb 2 S 3 , 21.512 mg; 15 CaSi 2 , 

3 TNT in gumarabic, binder. 

III. Flash powder mixture of Ti, Ni, and KC10 4 , 0.6g. Flame 
such that no free 0 4 is evolved. 

IV. Primer pressed mixture (37 Fe, 3 Zr, 10 Ba0 2 NaC10 3 20 
glass); 8 g mixed with 7% H,0 and dried. 

V. Cast cone 20 Fe, 60 NaC10 3 ,To BaO, 10 glass; 37 g em¬ 
bedded in candle. 

VI. Candle proper 10 Fe, 80 NaC10 3 , 4 Ba0 2 , 6 glass. 

1. The maximum temperature reaches 900-1000 
C. This exceeds the melting point of NaCl (804 C) 
and the evolution of oxygen causes violent ebullition 
and splattering of the molten material. It is therefore 
necessary to introduce a brass splatter guard directly 
over the ignition cones in order to prevent clogging 
of the filters. 

2. The top of the container may reach red heat 
(500 C or more) unless sufficient heat capacity is 
present. 


It is of interest that the Japanese ignition system 
also employs a cone of highly reactive iron-chlorate 
mixture embedded in the generating compound; in 
this case, however, the cone is ignited via a series of 
fuses which are initially fired by a hot wire oper¬ 
ated by the aircraft’s electrical supply. 

The candle substance is not easily ignited with an 
open flame. Once started, however, it will contribute 
violently to any general conflagration. Preliminary 
gun-fire tests carried out at Wright Field indicate 
that incendiary bullets will not ignite pressed candles 
containing 6 to 8% iron, but may ignite the 12% 
composition. No data of this nature have yet been 
obtained using standard OCA units containing cast 
candles. 



Figure 19. Statistical test of the ignition system of 
chlorate candles. 


Purity of Oxygen 

In addition to oxygen the evolved gas contains 
impurities in the form of a fine suspension of NaCl 
“smoke” and traces of C0 2 and CO. 

C0 2 and CO. As shown in Table 3 the concentra¬ 
tion of COz from the cast candles is less than 0.05% 
and the concentration of CO is approximately 
0.007%.' These low concentrations are in contrast 
to earlier chlorate oxygen generators which liberated 
relatively large quantities of these impurities (Table 
3). Since the deleterious physiological effects of CO 
depend primarily on the ratio of the partial pressures 
of CO to 0 2 , this concentration is too small to pro¬ 
duce measurable physiological effects. 


1 As estimated with the National Bureau of Standards 
Calorimetric CO Indicator. 

































OXYGEN FROM NON-REGENERATIVE CHEMICALS 


288 


NaCl Smoke. Each liter (STPD) of evolved oxygen 
contains approximately 5 mg of a fine suspension of 
NaCl particles. This smoke may be removed by fil¬ 
tration ; the most satisfactory filter found for this 
purpose is a fine Fiberglas mat which, after baking at 
400 C, is free of organic impurities. (AA Fiberglas 
mat, fiber size >4 micron diameter, manufactured by 
Owens-Corning Fiberglas Company, Toledo, Ohio.) 

Impurities from the Ignition System. The flash 
powder (0.6 g) is quantitatively transformed to NiO, 
TiOo and KC1 and these materials are deposited on 
the surface of the candle and on the inner walls of the 
container. The nickel contains about 1 % Hg as an 
impurity. The total quantity of mercury from this 
source is about 1.8 mg. It is unlikely that this 
amount could produce symptoms of mercury poison¬ 
ing in humans, even supposing all of it to reach 
the inspired gas once each day for two months. 3- 
However, should this prove advisable, mercury-free 
Ni may be substituted for the present impure mate¬ 
rial. 

The oxygen liberated from the primer and cast 
cone is contaminated with about 0.01% CO. 

12 3 3 Apparatus 

Factors Determining Design 

The chlorate candles described in Section 12.3.2 
may be used as a source of oxygen for a variety of 
purposes. However, each application may require the 
development of specialized equipment, the design of 
which is dependent partly upon the requirements of 
the problem and partly upon the decomposition char¬ 
acteristics of the candles. The following section is 
concerned with one such application, namely, the 
development of an expendable apparatus to provide 
a portable emergency oxygen source for aircraft per¬ 
sonnel equipped with standard demand masks. 

General Scheme. The general design and arrange¬ 
ment of parts is shown in Figure 20. Candle A is 
contained in a thin-walled metal container B from 
which it is insulated thermally by glass fiber C. 
Mounted in the upper end of the container and di¬ 
rected toward the sensitive primer P of the candle is a 
bouchon-type igniter D (see also Figure 18). In the 
top of the container B is located a gas take-off E 
leading to a flow indicator F and a hermetically 
sealed valve V which permits isolation of the candle 
from the ambient atmosphere until time of use. Ig¬ 
niter D and valve V are both released by rip cord 
R at time of use. Between the candle A and the gas 


take-off £ is a filter for removal of impurities (as 
discussed under Section 12.3.2) and a heat reser¬ 
voir H. The latter is intended to absorb excess heat 
generated during the ignition phase. After leaving 
valve V, the generated oxygen is conducted through 
a tube T to an economizer G which adapts the con¬ 
stant flow of oxygen to the intermittent requirements 
of breathing. The economizer is provided with a 
standard connection J for demand masks. Inasmuch 
as the container B may attain a local surface tem¬ 
perature of 400 C, a guard K is provided for protec¬ 
tion of hands and clothing. A flow indicator F is 
provided for ascertaining continuously the delivery 
of oxygen; the oxygen reserve is indicated by the 
color of a temperature-sensitive paint along one side 
of the container B. The entire apparatus weighs 3 lb, 
14 oz (of which 1 lb, 13 oz is candle) and may he 
fastened to the clothing by a standard spring clip. 

Details of Structural Elements 

Candle and Insulation. The cast candle is 10 in. by 
1 in. diameter and of composition 81-10-3-7. As 
shown in a preceding paragraph, the reacted and 
unreacted portions of the candle must he rigidly held 
in place in order to insure a constant flow of oxygen 
under conditions involving vibration or mechanical 
shock. In the present apparatus, the candle is sup¬ 
ported by the container B and a firm packing of glass 
wool, together with supports at each end. It is likely 
that the candle, thus supported, will not be injured 
by shocks in storage or in use, short of actual dam¬ 
age to the casing. 

The glass fiber packing surrounding the candle 
serves two purposes in addition to supporting the 
candle. The first is to filter from the generated oxy¬ 
gen much of the smoke formed in the decomposition 
of the chlorate. The second purpose is to provide 
thermal insulation between the candle and the metal¬ 
lic wall of the container, thus preventing the transfer 
of heat from the hot reaction zone down the metal 
wall to the unreacted portion of the candle. This pre¬ 
vents acceleration in the rate of evolution of oxygen 
which otherwise occurs when the chlorate composi¬ 
tion is preheated in advance of the zone of decompo¬ 
sition (Figure 17). For the same reason, the hot 
evolved oxygen is not permitted to pass in contact 
with the unreacted material, and provision is made to 
withdraw the oxygen from the reacted end of the 
candle. 

Candle Container and Protective Casing. The can¬ 
dle chamber B is made from brass tubing 11*4 in. 






SODIUM CHLORATE CANDLE APPARATUS FOR AIRCRAFT 289 



Figure 20. The oxygen candle apparatus [OCA], 


A 

B 

C 

D 

E 

F 

G 

H 

I. 

J. 


Candle proper 

Metal case—brass or tinplate 
Fiberglas filter, insulator and shock absorber 
Grenade ignition bouchon 
Gas take-off 

Flow indicator (spinner) 

Economizer 

Heat absorber (Hopcalite or KC10 4 ) 

Oxygen inlet to economizer 
Standard connection for mask hose 


K. Micarta-cork outer case 

M. Diaphragm for hermetic seal 

N. Ignition cone 
P. Primer 

R. Ripcord for starting ignition and breaking seal 

•S'. Blow-out patch, 50-80 psi 

T. Tube from seal valve to economizer 

V. Scale valve-containing spring-actuated lance for puncturing M 
Y. Diluter valve (A-13) 


long and 1% in. in diameter. For the production 
models NDRC had hoped to use 0.015-in. tinned 
iron sheeting, double seamed and brazed to give her- 
metical sealing. This proved to be unsatisfactory, 
largely because the increased heat dissipation through 
tin plate slowed the burning rate of the candles, the 
composition of which had previously been deter¬ 
mined from their behavior in experimental brass 
burners. Some thought has been given to the use of 
0.006-in. stainless steel which could be fabricated by 
welding. Any of these materials can be used pro¬ 


vided that suitable adjustments are made in the can¬ 
dle composition to compensate for changes in heat 
dissipation. 

The chamber is capable of withstanding several 
hundred psi; however, a safety disk S designed to 
burst at 50 to 80 psi is provided at the bottom of the 
container in order to avoid a hazardous rupture in 
the event of failure of the seal valve or accidental 
plugging of the oxygen outlet. 

The candle chamber is surrounded at a distance 
of y 2 in. from the surface by a perforated fiber 































290 


OXYGEN FROM NON-REGENERATIVE CHEMICALS 


(Micarta) guard mounted on supports of low thermal 
conductivity. The outer surface of the Micarta guard 
is coated with cork. The cork surface becomes un¬ 
pleasantly warm during operation of the unit at room 
temperature and in still air; however, it may be 
handled with bare hands without serious discomfort 
under these conditions. At ordinary operational tem¬ 
peratures + 10 to —10C the surface temperature is 
pleasantly warm. The Micarta-cork combination is 
the best of a number of materials which have been 
considered. An earlier solution of this problem in¬ 
volved a water jacket and fiber cover. In this form of 
the apparatus approximately 140 ml of water are 
evaporated from the jacket, thus absorbing 75,000 
cal or about one-half the total reaction heat. 

Heat Reservoir and Filter. The experimental 
models of the OCA were provided with a heavy brass 
head assembly used for recharging the unit. This had 
sufficient heat capacity to prevent excessive heating 
of the apparatus during the ignition phase. In the 
lighter, expendable production model, however, a sup¬ 
plementary heat absorber is required. This is the 
primary purpose of the Hopcalite or KC10 4 intro¬ 
duced below the filter (Figure 20-//). Twenty-five 
grams of these materials absorb about 3 kcal in the 
range 0 to 500 C, and this appears to be sufficient 
to prevent the apparatus from reaching red heat 
(500 C). 

Located in the top of the chamber (Figure 20) be¬ 
tween the candle A and the heat reservoir is a filter 
comprising wire screen disks which enclose two lay¬ 
ers of AA Fiberglas mat. This filter removes the 
NaCl smoke which is produced by the igniter cones 
or which otherwise escapes the glass mat surrounding 
the candle. A splatter guard is placed directly over 
the ignition cones in order to prevent clogging of the 
heat reservoir and filter with molten material from 
the igniter. 

The filtration pressure during the operational phase 
is of the order of 5 to 15 psi depending on the alti¬ 
tude and the duration of use. During the ignition 
phase the pressure may be as high as 25 psi at the 
time of peak flow. At altitude the increase in (ambi¬ 
ent) flow rate increases the filtration pressure and 
tends to maintain the absolute pressure within the 
container at a constant value. 

Igniter, Hermetic Seal Valve, and Rip Cord. The 
igniter bouchon of the hand grenade type (see Sec¬ 
tion 12.3.2) was machined from brass in order to 
withstand the intense heat during the ignition phase. 

Alongside the igniter is located the seal valve V 


containing a thin metal diaphragm M. Above the dia¬ 
phragm is a spring-loaded lance normally restrained 
by a pin. The lance mechanism is enclosed in a gas 
passage conducting the oxygen to the economizer G. 
The passage is further sealed from the release pin 
aperture by a gasket upon which the lance mechanism 
seats after release. 

The release pins for the igniter and seal valve are 
aligned and connected to a common rip cord, which 
also engages a dust cover for the top of the apparatus. 
The seal valve is arranged to open ahead of the firing 
of the igniter so as to preclude pressure buildup in 
the candle chamber. 

Floiv and Oxygen Reserve Indicators. The flow 
indicator consists of a small propeller or pin wheel in 
the oxygen stream. It occupies a chamber provided 
with a transparent, heat-resistant mica window. 
Every other blade is painted with heat-resistant 
aluminum paint and oxygen flow is indicated by 
flicker as the blades rotate. The chamber is included 
in the hermetically sealed part of the system in order 
to protect the moving parts from corrosion. 

The oxygen reserve indicator is a strip of tem¬ 
perature-sensitive lacquer (Tempilaq) painted on one 
side of the candle chamber. As the reaction front pro¬ 
ceeds down the candle, the painted strip on the out¬ 
side of the container melts to the level of the front. 
The height of the painted strip is therefore a measure 
of the oxygen reserve. Since the temperature gradi¬ 
ent is very large (see Figure 17) the choice of paint 
is not critical. Tempilaq, which melts in the range 
175 to 250 C, will indicate the oxygen reserve within 
10 % at all relevant ambient temperatures. 

Layering Economizer. Tbe generated oxygen 
passes from the candle chamber B through flow indi¬ 
cator F, seal valve E, and connecting tubing T to tbe 
oxygen inlet I of economizer (7. 33 It consists of a 
cylindrical reservoir 25 cm long and with a fixed vol¬ 
ume of about 300 ml. The reservoir is provided at the 
bottom with the inlet Y for the source oxygen flow 
and a “diluter” valve inlet M. The latter inlet com¬ 
municates with air via a standard A-13 inspiratory 
valve, loaded to about 2 mm FLO to prevent out¬ 
board leakage of oxygen. Connection with the de¬ 
mand mask is made with standard fittings J at the top 
of the reservoir. 

The economizer operates as follows. During ex¬ 
piration, oxygen from the candle displaces the con¬ 
tents of the reservoir through the expiratory valve of 
the mask. Oxygen stored in this way during expira¬ 
tion is then utilized during the succeeding inspiration. 




SODIUM CHLORATE CANDLE APPARATUS FOR AIRCRAFT 


291 


The volume in the inspiratory tube and in the mask 
(120 ml) is included in the functional storage system 
(total volume of 420 ml). 

The physiological characteristics of the system are 
shown in Figure 21. For example, reference to the 



Figure 21. Oxygen requirements based upon the layer¬ 
ing economizer. (Note: The oxygen candle apparatus is 
designed to conform to the right-hand ordinates.) 

right-hand ordinate of Figure 14 shows that an indi¬ 
vidual with a respiratory minute volume [RMV] 
of 25 1 per min BTPS using the OCA at an altitude of 
27,000 ft will be at a physiological altitude equivalent 
to sea level. It is evident that under most operational 


conditions (20 to 30,000 ft, respiratory minute vol¬ 
ume 15 1 per min or less) the OCA provides more 
than sufficient oxygen to maintain physiological con¬ 
ditions equivalent to sea level. The chief advantages 
of this form of economizer over the conventional flex¬ 
ible hag are (1) greater compactness and ruggedness, 
(2) reduced fire hazard, (3) freedom from danger of 
collapse during use, and (4) no deterioration in 
storage. 

An important limitation which this economizer 
shares with other free flow systems arises from the 
respiratory response to anoxia. If, for example, the 
source flow is set to maintain an altitude equivalent 
of 12,000 ft with a respiratory minute volume of 40 
1 per min (present apparatus) the resulting anoxia 
may cause an increased minute volume which, in turn, 
increases the equivalent altitude and sets in motion a 
cycle leading to respiratory distress and collapse. For 
steady state conditions, therefore, it is important to 
limit the use of the equipment to conditions in which 
little hyperventilation is likely to occur. 

The layering economizer provides a simple answer 
to the problem of adapting the constant flow of oxy¬ 
gen from the candle for use with standard demand 
masks. However, it does so at a considerable sacri¬ 
fice in delivery efficiency and this is particularly true 
under conditions of minimal respiratory activity at 
moderate altitudes where only a fraction of the oxy¬ 
gen provided by the candle is actually required to 
enrich the inspired gas. This is shown in Table 4, 


Table 4. Efficiencies of portable oxygen systems under certain operational conditions. 



Weight 

(lb) 

Duration 

(min) 

Storage 

Weight 0 2 

Weight equip 
X 100 

efficiency 

Lb 0 2 

Cu ft equip 
X 1.40 

Delivery 

efficiency 

Metabolic 0 2 

Supply 0 2 

Overall 

efficiency 

Man-min Man-min 
per lb per cu ft 

equipment equipment 

Standard A-4 walk-around 
with A-13 regulator 

3.1 

7 

4 

1.3 

14 

2.3 

50 

Experimental C-K rebreather 
emergency oxygen unit 

3.5 

90 

11 

8.4 

c40 

26 

1,500 

Oxygen candle apparatus 
present form 

3.8 

30 

16 

11.6 

16 

8 

400 

Standard A-6 walk-around 
with A-12 regulator 

5.1 

24 

6 

1.7 

20 

4.7 

100 

D-2 cylinder with A-12 regulator 

7.1 

50 

8 

2.1 

20 

7 

120 

A-2 high pressure with A-9 
constant flow regulator 

8.7 

50 

7 

5.2 

20 

6 

320 

NDRC experimental liquid oxy¬ 
gen-1 liter portable with arc A- 

■12 7.7 

200 

36 

14 

20 

26 

800 

Modified OCA for moderate 
altitudes, BLB mask (not built) 

2 

30 

18 

21 

23 

15 

1,200 


Assumptions. Altitude, 25,000 ft; temperature, 25 C; physiological activity light work equivalent to respiratory minute volume [RMV] 
20 1 per min BTPS or 5.6 1 per min STPD; metabolic oxygen consumption. 0.8 1 per min; oxygen flows, OCA 5.0 1 per min; A-13, 5.6 1 per 
min; A-12, 4.0 1 per min; A-9, 4.0 1 per min. Note: The overall efficiency of the OCA is independent of RMV whereas the efficiency of all 
other systems listed is inversely proportional to RMV. 






















292 


OXYGEN FROM NON-REGENERATIVE CHEMICALS 


which summarizes the storage, delivery, and overall 
efficiencies of various oxygen systems under certain 
operational conditions. It is seen that in spite of the 
sacrifice of delivery efficiency, the overall efficiency 
of the OCA in terms of man-minutes per unit weight 
or volume is considerably greater than that of present 
equipment. However, it is considerably less than 
that of the chlorate-primed KOX unit (rebreather 
unit for aircraft use) or of certain liquid oxygen 
supplies. (See next chapter.) 

12 3 4 Physiological Test of the OCA 

The greater part of the physiological testing of the 
OCA has been carried out on one or two individuals 
under conditions in which the oxygen flow to the 
economizer could be regulated. The tests included 
measurements of arterial oxygen saturation (oxi¬ 
meter) and inspired oxygen fraction as a function of 
work rate (bicycle ergometer), respiratory minute 
volume and oxygen flow from the candle at various 
altitudes and temperatures. 33 A number of physio¬ 
logical and practical tests have been conducted since 
this detailed analysis, principally with the early water- 
cooled model of the OCA containing pressed candles 
and phosphorus ignition. 

Use of the OCA for the Resuscitation of 
Unconscious Personnel at Altitude 

In four experiments the OCA has been used to 
revive persons rendered unconscious from lack of 
oxygen in the altitude chamber. The results of one of 
these experiments are shown in Figure 22. It is 
seen that a candle flow of 4.05 1 per min STPD was 
adequate to resuscitate the unconscious individual at 
30,000 ft. 

Use of the OCA with Mask Leaks 

In contrast to ordinary demand regulators, the 
OCA affords considerable protection against anoxia 
resulting from mask leaks. This is illustrated in the 
experiment of Table 5. 

Table 5. Protection against mask leaks. Subject: 
G.A.M. engaged in light physical activity; Mask A-12 
with orifice leak in microphone port; OCA water-cooled 
model, pressed candle, phosphorus ignition. 


Altitude 

Oxygen 

supply 

Orifice 

diameter 

Arterial saturation 
(oximeter) 

25,000 

Pioneer demand 

0.38 

Less than 70 

30,000 

OCA 

0.56 

97 

30,000 

Pioneer demand 

0.25 

Less than 70 

30,000 

OCA 

0.56 

100 


This characteristic of the OCA is a great advan¬ 
tage to its use in emergencies where mask leaks are 
likely to be present. 



Figure 22. Use of the oxygen candle apparatus (OCA) 
to revive unconscious personnel at altitude. “Pass-out” 
experiment at 30,000 ft. 


Practical Test of OCA with Retrained 
Subject in Simulated Emergency 

Three men with no previous knowledge of the 
OCA were subjected to a simulated altitude of 
30,000 ft at a temperature of —50 C. The men were 
given a 3-minute talk on the use of the OCA (water- 
cooled model, pressed candle, phosphorus ignition). 
Each man was issued a unit and two spare units were 
available in the chamber. Each man was given a task 
to perform while breathing from standard demand 
equipment. The oxygen supplying their regulators 
was cut off gradually without their knowledge. 

Subject A became anoxic from a mask leak and 
attempted to transfer to his OCA; he was unable to 
complete the transfer before becoming unconscious. 
Subjects B and C were busily engaged in the tasks 
allotted them and did not notice A’s plight. After 
waiting approximately ^ minute an observer ignited 
an OCA and fitted it to the unconscious man who re¬ 
covered completely in a few seconds. 

Subject B then noticed an increased resistance to 
breathing (caused by the unknown lowering of his 
regulator supply) and successfully transferred to his 
OCA. This subject had never before been in an alti¬ 
tude chamber and was unfamiliar with all oxygen 
equipment. 



















SODIUM CHLORATE CANDLE APPARATUS FOR AIRCRAFT 


293 


Subject C likewise noticed the increased resistance 
to breathing and successfully transferred to his OCA. 
The candle in this unit had been prepared so that it 
would go out unexpectedly after four minutes of 
operation and no flow indicator was provided. The 
candle was broken and a ring of brass and asbestos 
inserted in the break. After five minutes the subject 
became anoxic and started coughing as a result of 
fumes from the hot asbestos. Subject A, who was 
using the same unit that had revived him 13 minutes 
earlier, ignited a spare OCA and fitted it to Subject 
C. Ten minutes later the chamber was brought to 
sea level, all subjects remaining on their OCA units. 

12. 3 5 Potential Use of Chlorate Oxygen 

in Aircraft 

Suggested Further Developments 

Modification of Present OCA for Use or Indi¬ 
vidual, Portable Oxygen Supply in Transport Planes 
at Moderate Altitudes. As discussed in Section 

12.3.3 and Table 4, much of the potential efficiency 
of chlorate oxygen is sacrificed in the present form 
of the OCA in order to allow its operation with 
demand masks under extreme conditions of altitude, 
physiological activity, and low temperature. We now 
consider how the efficiency may be increased for 
applications involving less stringent conditions. 

It is evident from Table 6 that the weight and size 


Table 6 . Modified design characteristics of OCA for use 
at moderate altitudes with A-9 mask. 


Maximum operating altitude 

28,000 ft 

Max resp min vol for equivalent alti¬ 
tude of 5,000 ft at operational al- 

titude of 28,000 ft and —20 C 

25 1/min BTPS 

Mask, constant flow with self-con- 

tained economizer and rebreather 

A-8 

bag 

Properties of candle 

Diameter 

3.1 cm, 1.2 in. 

Length 

25.4 cm, 10 in. 

Composition 

82-7-4-7 

Oxygen flow, —20—25 C 

3.2-3.8 1/min 

Duration, —20,—25 C 

30 to 36 min 

Total volume of equipment (approx) 

024 cu ft 

Total weight of equipment (approx) 

21 b 

Overall efficiency 

Man-min per cu ft 

1250-1500 

Man-min per lb 

15-18 


of the present OCA could be halved for moderate 
conditions of altitude, physiological activity, and low 
temperature. 


Chlorate Oxygen to Supply Several Persons at 
Moderate Altitudes. Semi-Portable Equipment. A 
slight further increase in overall efficiency may be 
obtained from chlorate oxygen in apparatus designed 
to supply several persons simultaneously. Such ap¬ 
paratus could be employed in aircraft which ordi¬ 
narily have no oxygen installations although it would 
not be portable in the sense of the individual supply. 
Table 7 shows the expected characteristics of a 


Table 7. Chlorate oxygen installation 5 persons mod¬ 
erate altitude. 


Max operating altitude 

28,000 ft 

Max resp min vol for equivalent alti¬ 
tude of 5,000 ft at operational al- 

titude of 28,000 ft and —20 C 

25 1/min BTPS 

Masks, constant flow with self-con¬ 
tained economizer and rebreather 

bag 

A-8 

Properties of candle 

Diameter 

7.6 cm, 3 in. 

Length 

51 cm, 20 in. 

Composition 

81-8-4-7 

Oxygen flow, —20, 25 C 

15-19 1/min STPD 
3.0-3.8 1/min 
per man 

Duration, —20, —25 C 

72-90 min 

Total volume of equipment (estimated) 

0.25 cu ft 

Total weight of equipment (estimated) 

181b 

Overall efficiency 

Man-min per cu ft 

1400-1700 

Man-min per lb 

20-25 


chlorate system designed to supply 5 persons for 70 
to 80 min at moderate altitudes. 

On the Design of Bail-out Equipment. It is evident 
from a consideration of Figure 19 that the flow rate 
from chlorate candles may be varied as a function of 
time to give a variety of flow patterns by suitable 
adjustment of the ignition system and candle diam¬ 
eter. The weight of candle required to duplicate the 
flow pattern of the H-2 cylinder is 8 oz and its volume 
is approximately 0.04 cu ft. It is therefore probable 
that a chlorate bail-out oxygen unit could be con¬ 
structed which would be less than one-half the weight 
and volume of present equipment. 

Use of Chlorate Oxygen for Medical Therapy. It 
was proposed to prepare chlorate candles of a suitable 
size to generate about 25 1 of oxygen per min for a 
period of 1 hr, to encase these candles in sealed light 
metal containers provided with smoke filters, Hop- 
calite, and igniter mechanism. A rack would hold 
one or more of these units and provide cooling coils, 
humidifier, and connection to an oxygen distributing 










294 


OXYGEN FROM NON-REGENERATIVE CHEMICALS 


line to patients in a ward or field treatment tent. In 
operation, a number of units providing the desired 
oxygen flow would be ignited and inserted in the 
rack; an attendant would replace spent units with 
fresh ones once an hour. Units of suitable rate and 


duration could be supplied for specific uses. The 
apparatus is simple and compact, and the chlorate 
units would be lighter and more compact than cylin¬ 
ders containing an equivalent amount of compressed 
oxygen. 



Chapter 13 

LIQUID OXYGEN VAPORIZERS FOR AERONAUTICAL, 
MEDICAL AND ENGINEERING USES 

By S. S. Prentiss a 


INTRODUCTION 

nlike carbon dioxide and some hydrocarbon 
gases, oxygen gas cannot be compressed to a 
liquid at normal ambient temperatures. At normal 
temperatures, oxygen behaves as a noncondensable 
gas so that the advantages of high density (small 
volume) can be attained only at the expense of high 
pressures. On the other hand the great density of 
liquid oxygen can be obtained only at very low tem¬ 
peratures (—148 C at 1 atm pressure) by the use of 
the highest order of thermal insulators (nonradiating 
vacuum jackets) if the storage period is to be useful. 

The use of liquid oxygen as a source of oxygen for 
aviation and medical breathing requirements, engi¬ 
neering uses, with on-the-spot conversion to gas, in¬ 
volves a number of factors representing, in the ag¬ 
gregate, a complex problem which has not been read¬ 
ily solvable in connection with military problems 
during the war. 23 As a result, the development of 
oxygen vaporizing equipment, 13 although not difficult 
from an engineering point of view, has made slow 
progress because the desire of the military for such 
apparatus has blown alternatively hot and cold over 
recent years. 

Some of the factors may be mentioned as illustra¬ 
tive of this problem. 14 ’ 18 ’ 19 The availability of liquid 
oxygen has very recently improved to the point that 
serious consideration could be given to its use at 
advance bases and combat areas. Small, portable 
liquid oxygen producing plants have been developed 
which can be moved into, and operated at, forward 
areas. Liquid oxygen has been available in quantity 
for a number of years in industrial areas of the United 
States and suitable equipment for storage and trans- 


11 Technical Aide, Division 11, NDRC. 
b Apparatus for converting liquid oxygen to gaseous oxy¬ 
gen under controlled conditions has been variously designated 
liquid oxygen vaporizers, liquid oxygen converters. Appara¬ 
tus of chief concern in this chapter relates to vaporizers or 
converters for supplying gaseous oxygen at relatively low 
useful pressures, on a demand basis, to a using device such 
as breathing equipment, and cutting and welding torches, 
at a relatively low operating pressure. Apparatus for vapor¬ 
izing liquid oxygen for the purpose of charging compressed 
gas cylinders at high pressures is touched upon briefly. 


portation is available. 21 The remarkable advantage 
of small, light weight liquid oxygen equipment over 
compressed gas equipment of comparable capacity is 
of greatest significance aboard aircraft, but the re¬ 
quirements for aircraft oxygen systems have not re¬ 
mained constant with regard either to capacity or 
rate of delivery. Aircraft not regularly functioning 
at higher altitudes and aircraft carrying one or two 
crew members only, require so little oxygen that 
advantages of liquid oxygen system over gaseous 
oxygen systems are insignificant while the difficulties 
are magnified. However, as aircraft requiring larger 
crews were regularly operating at higher altitudes 
and the cruising range was increased, the necessity 
for carrying large quantities of oxygen again called 
attention to the advantages of liquid oxygen. These 
factors did not culminate in an all-out effort to pro¬ 
duce liquid oxygen installations for military aircraft 
until the last year of the war. 

Other delaying factors should be mentioned, 
namely, a great advance in the recognition of physio¬ 
logical requirements for oxygen and the development 
of improved dispensing equipment such as demand 
regulators and oxygen masks, requiring constant 
modification of the oxygen supply system. xAgain 
this was not too difficult from the engineering point 
of view but the constant changes in specifications for 
the oxygen vaporizer hampered the construction of 
experimental units. 

13 2 PROPERTIES OF OXYGEN 26 

The variation of the boiling point and vapor pres¬ 
sure of liquid oxygen with absolute pressure is given 
in Figure 1. 

The latent heat of vaporization at the boiling point 
is equal to 50.8 cal per g or 91.51 Btu per lb. The 
latent energy required to vaporize liquid oxygen at 
the boiling point and raise the temperature of the 
gas to 20 C is approximately 88 cal per g or 160 Btu 
per lb. This is equivalent to 4 kwh per 1,000 cu ft 
of oxygen. 

The specific heat of the gas ( C v ) is equal to 0.218 
cal per g C. The specific heat of liquid oxygen at 
—200 C is equal to 0.393 cal per g C. 



295 



296 


LIQUID OXYGEN VAPORIZERS 


The specific gravity of liquid oxygen at 1 atm is 
1.14 and this decreases approximately 14% at a 
pressure of 100 psi and 30% at a pressure of 400 psi. 
One liter of liquid oxygen at atmospheric pressure 
produces approximately 800 1 of gaseous oxygen at 
20 C and 1 atm pressure. 



TEMPERATURE F 


Figure 1. Effect of vapor pressure on boiling point of 
liquid oxygen. Note: TC in zero degrees Farenheit 
(-182 F). 

It will he apparent that the energy requirements of 
a vaporizer will vary considerably with the pressure 
range over which the vaporizer is operated. For 
example, starting with 25 1 of liquid oxygen at 1 atm 
absolute pressure, it will he necessary to supply 225 
kcal to warm this body of liquid to a temperature at 
which the boiling point is equivalent to 5 atm abs, 
or an operating gauge pressure of 60 psi. 

13 3 TYPES of liquid oxygen 
VAPORIZERS 

Based upon different principles of operation, six 
types of liquid oxygen vaporizers are suitable for 
aviation and other military purposes. Division 11 
of NDRC has contributed improvements to four of 
these types and these will he discussed in detail below. 

Type 1. Liquid oxygen is held under operating 
pressure in a container with suitable thermal insula¬ 
tion and withdrawn therefrom through a length of 
metallic tubing with sufficient exposure to the at¬ 
mosphere to evaporate the liquid oxygen and warm 
the resulting gas. This is the simplest form of ap¬ 
paratus which might he used for the purpose and is 
basic to some of the following types in which refine¬ 
ments are added to control carefully the operating 
pressure. An example of such vaporizers is that 


produced at the University of California 2 for the 
operation of cutting and welding torches. An alterna¬ 
tive form of the apparatus has the liquid oxygen con¬ 
tainer at atmospheric pressure from which liquid 
oxygen is delivered by means of a pump through 
vaporizing and warming coils 13 (see Chapter 6). 

Type 2. A small, poorly insulated reservoir pro¬ 
vided with atmospheric vaporizing coil and automatic 
pressure controls is connected to a larger well-insu¬ 
lated reservoir from which it is charged at frequent 
intervals during operation. Early apparatus devel¬ 
oped by Akerman at the University of Minnesota was 
of this type. 3 ’ 7 ’ 24 

Type 3. Atmospheric vaporizing coils and auto¬ 
matic pressure controls are combined directly with a 
well-insulated reservoir in which the entire charge of 
liquid oxygen can be stored for appreciable lengths 
of time. Later models of the Akerman vaporizer, con¬ 
structed upon metal Dewar containers, are of this 
type. 6,25 

Type 4. Liquid oxygen, at a temperature corre¬ 
sponding to a boiling point less than the desired oper¬ 
ating pressure, is contained in a vessel equipped with 
means for subjecting the gos phase to additional pres¬ 
sure until the desired operating pressure is obtained. 
Preferably the gas phase is pressurized by the evapo¬ 
ration of a small amount of liquid withdrawn from 
the container. The heat requirement for pressurizing 
this type of vaporizer from liquid, initially at atmos¬ 
pheric pressure, is considerably less than that re¬ 
quired when the whole body of the liquid must be 
raised to a boiling point equivalent to the operating 
pressure. This type is represented by vaporizers by 
Piccard 3 and Wildhack. 20 

Type 5. Liquid oxygen is contained in a well- 
insulated container such as a Dewar flask equipped 
with electric heating coils in the liquid phase. The 
electric heating circuit is provided with automatic 
pressure controls and serves to pressurize the appara¬ 
tus when the liquid oxygen is initially at atmospheric 
pressure and also to vaporize and deliver gaseous 
oxygen therefrom. Such vaporizers have been de¬ 
veloped by Mathis and Milan 10 and Linde Air 
Products Company. 12 In a refinement developed by 
Arthur D. Little, Inc., the liquid oxygen is absorbed 
in a mass of fine glass fiber in which is embedded the 
electric heating element; liquid oxygen so confined 
will not spill and operation is independent of position. 

Type 6. Pressure control and part of the heat of 
vaporization is furnished by an electrical system to 
which is added vaporizing coils warmed by the am- 




TYPE 1—GIAUQUE LIQUID OXYGEN VAPORIZER 


297 


bient atmosphere. Such a combination vaporizer has 
been developed at the University of Toronto. 15 

Inasmuch as Division 11 has made no contribution 
to types 5 and 6, they will not be further discussed 
in this report. It should he noted, however, that the 
electric energy required for pressurizing the equip¬ 
ment in a short time and for maintaining oxygen de¬ 
livery (5 w per 1 per min STP) required on aircraft, 
constitutes an appreciable drain upon the electrical 
facilities of the aircraft and for this reason the de¬ 
velopment of vaporizers depending entirely upon 
ambient heat appeared desirable. 

13 3 1 Note on Use of Liquid Oxygen 
Vaporizers Developed by 
Division 11 

The most stringent requirement for liquid oxygen 
vaporizers has been in the field of aircraft installa¬ 
tions and for this reason the principal effort has been 
in this direction. It is felt that the vaporizers devel¬ 
oped for this use will he directly useful also in the 
field of therapeutic administration of oxygen in hos¬ 
pitals, although some of the controls will not he 
required. Although the aircraft units will operate 
cutting and welding torches in the field satisfactorily 
they have not been constructed with sufficient 
strength and ruggedness to withstand this usage. 
Emphasis on low weight is not present in field engi¬ 
neering apparatus and it may he that the presently 
developed units will he suitable for this use when 
provided with protective casings. Large units for 
permanent aircraft installations do not have the severe 
conditions of operations placed upon them that occur 
when the corresponding unit is to he used as a small 
or portable model for walk-around service and, there¬ 
fore, the development of such portable units consti¬ 
tutes a special problem. 

13.4 TYPE 1—GIAUQUE LIQUID 
OXYGEN VAPORIZER 

A simple form of liquid oxygen vaporizer suitable 
for the operation of cutting and welding torches, oxy¬ 
gen therapy, and perhaps also for oxygen supply on 
aircraft (within limits) is shown in Figure 2. The 
vaporizer apparatus shown on the left of the figure 
is attached to the vacuum-jacketed Dewar container 
shown on the right of the figure by means of a screw 
fitting soldered to the neck of the container. This 
vaporizer consists of a tube of stainless steel or other 


material of low heat conductivity which dips to the 
bottom of the liquid in the container, a gas-tight con¬ 
nection for the vapor phase above the liquid in the 
container, an external coil of tubing connected di¬ 
rectly to the dip tube extending to the bottom of the 
container, and pressure gauge and safety valve con¬ 
necting to the gas phase. The container may be 
pressurized in a number of ways; for example (1) 
by pulling oxygen from a cylinder through the liquid 
until the temperature of the liquid is raised to the 



Figure 2. Liquid oxygen vaporizer. 


desired boiling point, (2) by allowing the container 
to stand until the liquid is warmed by natural beat 
leak or accelerated by laying the container upon its 
side, whereby beat is rapidly introduced through the 
neck of the container, or (3) by introducing dry gas 
directly into the gas phase above the liquid. After 
pressurizing, gas may be withdrawn from the ex¬ 
ternal end of the evaporator tubing through a suitable 
needle valve or reducing valve. During such with¬ 
drawal, liquid oxygen enters the vaporizing tubing 
and is vaporized and warmed therein. Vaporization 
and withdrawal of oxygen, therefore, occurs auto¬ 
matically upon a “demand” basis. The pressure 
within the container is limited by suitable adjustment 
of the safety valve. The effectiveness of the vapor- 















298 


LIQUID OXYGEN VAPORIZERS 


izer tubing may be enhanced by the insertion of a 
twisted strip of brass to serve as a turbulator. 

The following information applies to the apparatus 
illustrated in Figure 2. The coil shown consists of 

12 ft of ^-in. copper tubing with a turbulator strip 
0.255 in. wide and 0.033 in. thick, twisted 5 turns 
per ft and pulled through the ^-in. tube before it 
was coiled. 

A needle valve, shown with the vertical hose con¬ 
nection attached, is used to control the rate of gas 
flow. The horizontal needle valve is provided for 
pressurizing the gas phase of the container from an 
external source of dry gas under pressure. 

The 50-1 container will supply 1,500 cu ft of oxygen 
gas STP per filling. The vaporizer is designed to 
deliver 1 cfm of oxygen warmed to ordinary tem¬ 
perature, which amount is sufficient to enable an 
oxyacetylene torch to cut 24-in. steel plate at the 
rate of 1 ft per min. If greater rates of flow are 
desired, vaporizer tubing may be increased in length 
and/or diameter. 

There is little tendency for liquid convection when 
compressed air or other gas is admitted over liquid 
oxygen as the equilibrium liquid at the surface would 
be less dense by about 0.2 g per ml. 

13 5 TYPE 2—EARLY AKERMAN LIQUID 

OXYGEN VAPORIZER 0 

Refinements of the apparatus just described ap¬ 
peared to be necessary for aircraft use. These re¬ 
finements provided for operation at constant abso¬ 
lute pressure and a certain degree of economy when 
the apparatus stands for long periods of disuse. 

The principles of operation of the vaporizer are 
shown in Figure 3 and the apparatus in Figure 4. 
Liquid oxygen is contained in a thin-walled metallic 
container B surrounded by thermal insulations which 
in turn is encased in a vessel A capable of withstand¬ 
ing the operating pressure of the system. There is 
a small space provided between the inner, thermally 
insulated container and the outer pressure casing. 
Tube O connects the liquid phase in the inner con¬ 
tainer with this space between the containers. When 
the system is under pressure and the pressure is 
equalized between the inner container and the outer 


c An early form of this apparatus 24 was developed by the 
University of Minnesota. Subsequently an NDRC contract 
was arranged with the University of Minnesota in order 
that the development might be better adapted to flight re¬ 
quirements as specified by the Navy Bureau of Aeronautics. 


container, no liquid will flow through the tube. FIow- 
ever, if gas is withdrawn from the outer container, 
thus lowering the pressure slightly, liquid will be 
caused to flow through tube O into the space between 
containers E, where it will be rapidly vaporized 
through heat transfer with the outer container. The 
rate of evaporation, for continuous operation, is 
limited by the heat transfer between the outer casing 
and the ambient atmosphere. 



B SILVER BOTTLE (15 LITER) H PRESSURE OPENED BY-PASS 

S INSULATION H 1 MANUALLY OPENEO BY-PASS 

A CAST ALUMINUM PRESSURE (PETCOCK*l) 

VESSEL K OUTLET THROUGH FILTERS TO 

0 SPILLING TUBE DEMAND SYSTEM 

L PRESSURE POP-OFFS C BAFFLE PLATE 

J PRESSURE GAUGE D FILLING TUBE 

Figure 3. Akerman liquid oxygen converter. 

A pressure-opened by-pass valve H connects the 
gas phase C directly over the liquid with the vaporiza¬ 
tion chamber E between the inner and outer con¬ 
tainers. When this by-pass valve is open, the pres¬ 
sure between the inner liquid container and the 
vaporization chamber is, at all times, equalized and 
no liquid will be transferred to the vaporization 
chamber. Instead, the liquid C will be vaporized 
when gas is withdrawn and the temperature, and 
hence the pressure, will be gradually lowered. In 
operation, the pressure-opened by-pass valve H is 
adjusted to open and close at the minimum operating 
pressure desired in the system. If the pressure in 
the system is initially above this minimum pressure 
and gas is withdrawn, the pressure will gradually fall 






































TYPE 2—EARLY AKERMAN LIQUID OXYGEN VAPORIZER 


299 



DEWAR 

FLASK 


PETC0CK*3 

PETC0CK*4 


SAFETY 

VALVE*4 


SAFETY 
VALVE*3 


PETCOCK*2 


Figure 4. Photograph of Akerman liquid oxygen converter. 


until the minimum pressure is reached, whereupon 
the by-pass valve will close and further withdrawal 
will cause transfer of liquid to the vaporizing cham¬ 
ber. 

The apparatus is provided with suitable connec¬ 
tions and vents D, H, K for filling with liquid oxygen 
and a dual set of safety valves L. The vaporized oxy¬ 
gen is caused to pass through a suitable filter for 
the removal of odorous impurities. A large storage 
reservoir (a standard 50-1 Dewar container) is pro¬ 
vided in which the liquid is contained at a pressure in 
the neighborhood of operating pressure. 

The experimental model of the vaporizer weighs 
42 lb empty and can be charged with 15 1, or 34 lb, 
of liquid oxygen. The outer container is of aluminum. 
The inner container has a thin-walled silver sphere 
surrounded with rock wool insulation. 

The safety valves were adjusted to pop at about 


75 to 80 psi and the pressure-controlled by-pass 
valve was set at 45 psi. Therefore, the maximum 
pressure attained on standing is 75 to 80 lb and the 
minimum operating pressure is 45 lb. The vaporizer 
maintains a flow of approximately 100 1 of oxygen gas 
per minute STP continuously, or higher rate of flow 
for short periods of time. Heat leak through the 
thermal insulation is sufficient to vaporize approxi¬ 
mately 10 1 of oxygen STP per min. When charged 
with liquid oxygen at ambient pressure and allowed 
to stand, this heat leak is sufficient under normal 
conditions to raise the pressure to 45 psi gauge in 
17 to 20 min or to the pop-off pressure in 35 to 45 
min. This rate of evaporization loss is, in general, 
too high for storage purposes and, therefore, the 
main body of the liquid oxygen should be stored in 
the Dewar reservoir in which evaporization losses 
run from 3% to 5% in 24 hr. 














300 


LIQUID OXYGEN VAPORIZERS 


A feature of this apparatus is the pressure-control 
by-pass valve which was constructed with an evacu¬ 
ated sylphon control element providing maintenance 
of constant absolute minimum operating pressure at 
all altitudes. This was originally thought desirable 
but in the event that it is more advantageous to 
maintain constant gauge pressure, a by-pass control 
valve could be substituted which maintains a con¬ 
stant differential with the ambient pressure. 

Several schemes were proposed for causing this 
apparatus to operate satisfactorily in an inverted 
position for long periods of time. 3 The simplest 
arrangement to attain this end is to make all con¬ 
nections to the gas phase in the liquid oxygen con¬ 
tainer to a tube which opens in the center of the 
spherical container and to arrange that this con¬ 
tainer is at all times a little less than half full of 
liquid. 

13 6 TYPE 3—IMPROVED AKERMAN 
VAPORIZER 

13 61 Description 

The vaporizer just described had the disadvantages 
of (1) unnecessary weight, (2) high evaporation 
losses, and (3) complicated construction unsuited to 
production. 

Several later models were developed in which a 
standard spherical Dewar container was equipped 
with a vaporizing chamber in the form of a double- 
walled cylinder. The control features of pressure- 
operated by-pass valve, syphon tube for transfer of 
liquid oxygen, safety valves, etc., were retained. One 
of these vaporizers of 5-1 capacity is shown in Figure 
5 and a diagrammatic sketch in Figure 6. The opera¬ 
tion of this model is similar to type 2. In Figure 6, 
liquid oxygen C in container A-B passes through 
the central tube and valve F to the ring-shaped evapo¬ 
rating chamber E when gas is withdrawn at K. When 
the pressure in the system exceeds normal operating 
pressure, pressure-controlled by-pass valve H opens, 
equalizing the pressure between the gas and liquid 
phases preventing further discharge of liquid to E 
until the pressure again falls to normal operating 
valve. \ alves D, E and G are useful when the con¬ 
tainer is filled with liquid. A small container / may 
be filled with liquid oxygen, which, on vaporizing, 
assists in pressurizing the apparatus. In later models, 
I is arranged to discharge liquid directly into the 
vaporizing chamber (coils) so that the additional heat 


transfer surface may be utilized. / is a pressure 
gauge, L a safety valve. 

In a still further improvement, a coil of tubing 
was substituted for the double-walled vaporizer and 
the tubing, control regulators, safety valves and all 
other apparatus were compactly arranged around the 
neck of a standard Dewar container of 25-1 capacity. 
This apparatus is illustrated in Figures 7 and 8. 

When a Dewar container was used, the heat leak 
into the liquid oxygen was so small that several days 
were required to attain operating pressure on normal 
standing. This time could be greatly decreased by 
inverting the apparatus and thus introducing heat 
through the neck of the flask. However, the best 
method consisted in bubbling oxygen gas directly 
into the liquid. This oxygen gas could be obtained 
from an external source such as a cylinder of com¬ 
pressed gas or a small portion of liquid could be 
withdrawn from the apparatus into an auxiliary 
reservoir, vaporized and warmed in the main evapo¬ 
rator coils and then returned to the main body of the 
liquid. By such a procedure enough heat could be 
transferred in a few minutes to raise the vapor pres- 
' sure of the liquid to 50 or 60 psi. 

13 6 2 Operation of Type 3 Vaporizers 

The vaporizer shown in Figure 5 was tested under 
various conditions including installation in the alti¬ 
tude chamber of the Johnson Foundation, in both 
the warm and the cold. 11 The results of these tests 
under simulated flight conditions with a number of 
subjects is summarized in Table 1 ; the experimental 
set-up is illustrated in Figure 9. 

Physical characteristics of the model shown in 
Figures 7 and 8 exclusive of the portable unit are: 


Height, overall 

29 in. 

Outside diameter 

19 in. 

Weight, empty 

60 lb 

Weight, full 

120 lb 

Weight of liquid oxygen 

601b 

Length of vaporizing coil 

50 ft 

Operating pressure 

52 psi 


The following performance tests were obtained 
with this model. 

The converter was filled in 13 min from a warm 
state through a Jfj-in. diameter tube from a storage 
tank pressurized at 10 psi. With the storage tank- 
pressurized at 20 psi and with the converter cold, 
the filling process required 6 min. 

Inasmuch as this model had not been equipped 



301 


TYPE 3—IMPROVED AKERMAN VAPORIZER 


FLOWMETER 


GAS FILTERS 



DEWAR FLASK 


FILLING TUBE 


FILLING VALVE 
SPILLING TUBE PLUG VALVE 
BY-PASS NEEDLE VALVE 
PRESSURE GAUGE 
LIQUID LEVEL INDICATOR 
EVAPORATING CHAMBER 



Figure 5. Five-liter vaporizer. 


with self-pressurizing apparatus, an operating pres¬ 
sure was produced by bubbling gaseous oxygen under 
pressure through the liquid phase. When an equilib¬ 
rium pressure of 52 psi was reached, the pressure 
remained constant, regardless of flow conditions, 
until the liquid oxygen supply was exhausted. 

The flow was maintained at 100 1 per min for 1 hr. 


The temperature of the oxygen at the coil outlet de¬ 
creased slowly until at the end of the hour it was 30 
below the ambient temperature of 70 F. At the end 
of the hour the flow was suddenly increased to 400 
1 per min, ambient, whereupon the temperature of 
the oxygen at the coil outlet dropped to —100 F in 
1.25 min. 












302 LIQUID OXYGEN VAPORIZERS 







Table 1. 

Test 

results of 5-liter vaporizer. 





Ambient 

temp 

C 

Time 

period 

min 

Altitude No. of Auto¬ 
feet subjects mix 

o 2 

Work consump 

condition tion oz 

Line 

pressure 

psi 

Gas temp 
at 

flowmeter 

C 

O, 

liters 

STPD 

°> 

liters 

ATPD 

O, 

liters 

BTPS 

Average 
flow rate 
1/min 
STPD 

Average 
flow rate 
1/min 
ATPD 

Average 

minute 

volume 

per 

subj ect 
BTPS 

22 

6.5 

SL 

7 

Off 

Exercise 

56 

43-47 


1060 

1130 

1290 

163 

172 

28.5 


5 

SL 

7 

Off 

Rest 

14 

45-48 


276 

295 

336 

55 

59 

9.6 


5 

20,000 

7 

Off 

Exercise 

22 

41-44 

6 

436 

1040 

1250 

87 

208 

35.6 


5 

20.000 

7 

Off 

Rest 

8 

43-44 

11 

158 

367 

454 

32 

73 

13.0 


5 

20,000 

7 

On 

Exercise 

13 

42-44 


256 

600 

734 

51 

120 

21.0 



20,000 

7 

Off 



42-47 

(deep breathing in 

unison) 






5.5 

28,000 

7 

Off 

Rest 

4 

47 

11.5 

79 

259 

341 

14 

47 

8.9 


5 

28,000 

7 

Off 

Exercise 

11 

46-48 

11 

218 

719 

940 

44 

144 

26.8 



28,000 

7 

Off 



46-47 

(deep breathing in 

unison) 






5 

35,000 

6 

Off 

Rest 

3 

48.5 

12 

60 

272 

394 

12 

54 

13.1 


5 

35,000 

6 

Off 

Exercise 

10 

47-48 

13 

198 

900 

1300 

40 

180 

43.3 

-40 

5.5 

SL 

8 

Off 

Rest* 

25 

43-46 


496 

425 

602 

90 

77 

13.7 

• 

5 

20,000 

7 

Off 

Rest* 

9 

53-54 


178 

332 

510 

36 

66 

14.6 


5 

20,000 

6 

Off 

Exercise 

22 

52-54 


435 

812 

1230 

87 

162 

41.0 


10.5 

27,000 

7 

Off 

Rest* 

16 

53-54 


317 

796 

1285 

30 

76 

17.5 


5 

27,000 

7 

Off 

Exercise 

17 

52-53 


337 

848 

1368 

67 

170 

39.0 


5 

35,000 

7 

Off 

Exercise 

13 

53-54 


258 

940 

1700 

52 

188 

48.5 


* Subjects did not remain quiet during rest periods because of insufficiently heated clothing. 


D 



A converter was then mounted at an angle of 60 
degrees from the vertical and the test just described 
was repeated with similar results. 



Figure 6. Revised Akerman liquid oxygen evaporator. 


Figure 7. 25-liter vaporizer. 
































































TYPE 3—IMPROVED AKERMAN VAPORIZER 


303 



Figure 8. Details of 25-liter vaporizer. 


The converter was inverted, the flow of oxygen 
was maintained at 100 1 per min ambient for a period 
of 6 min. At the end of 6 min the temperature of the 
gas at the coil outlet was within 10 F of the ambient 
temperature. When the flow was increased to 400 
1 per min ambient, the temperature of the exit gas 
dropped approximately 30 F in 3 min. 

The converter was next tested at a temperature 


of —55 F with results quite similar to those obtained 
at room temperature with the exception that a flow 
of 400 1 per min caused the temperature at the coil 
outlet to fall almost immediately to a temperature of 
—100 F. the limit of the measuring instrument. 

Tests conducted with the converter in an atmos¬ 
phere at 100 F and 95% relative humidity gave 
results very similar to those obtained at normal 
ambient condition. 

After completion of performance tests, the con¬ 
verter was subjected to acceleration test of 9 g with 
a 32-lb load of liquid oxygen; a second acceleration 
test to 9 g with a 60-lb load of liquid oxygen; a 25-hr 
vibration test at a displacement of 0.025 in. and at a 
frequency cycling from 6 to 42 cycles per second, 
once every minute with converter empty; a similar 
test with converter containing 31 to 37 lb of liquid 
oxygen; a sloshing test with converter containing 60 
11) of liquid oxygen and rocking about 7 degrees 
from the vertical, from one side to the other, once 
every cycle at a rate of 35 cycles per min for 110 min ; 
and a third acceleration test to 9 g with 60 lb of 
liquid oxygen in the converter. Vaporization losses 
were measured over night during this test procedure; 
no significant changes were observed. 



Figure 9. Flow sheet of Akerman vaporizer. 





















































304 


LIQUID OXYGEN VAPORIZERS 


After the aforementioned tests were made the 
vaporizer was modified by the removal of the filter 
and the substitution of a small reservoir of 1-1 capa¬ 
city in place of the filter, with suitable connections to 
permit its use in the build-up of the initial operating 
pressure according to the following procedure. The 
reservoir is provided at the top with a connection to 
the liquid oxygen spill tube through a two-way valve 
which alternately connects the liquid oxygen spill 
tube to the bottom of the vaporizing coil for normal 
operation. The bottom of the auxiliary reservoir 
connects through a valve to the top of the vaporizing 
coil. The auxiliary reservoir also has a valve which 
vents directly to the atmosphere. In operation the 
converter is filled with liquid oxygen in such a man¬ 
ner that a pressure of at least 2 or 3 psi is present. 
The two-way valve is then adjusted to connect the 
liquid oxygen in the Dewar container with the aux¬ 
iliary reservoir and the vent valve to the atmosphere 
is opened. The initial pressure in the converter will 
then force the liquid over into the auxiliary reservoir 
until the latter is filled, whereupon the vent valve to 
the atmosphere is closed, the two-way valve read¬ 
justed to connect the liquid oxygen tube with the 
bottom of the vaporizing coil, and the valve between 
the bottom of the auxiliary reservoir on the top of 
the vaporizing coil is opened. Liquid oxygen from 
the auxiliary reservoir is thereupon forced into the 
vaporizing coil, where it is vaporized and warmed to 
approximately ambient temperature. It then passes 
into the main body of liquid oxygen in the Dewar 
container where it is condensed, thus warming and 
raising the pressure within the system. This process 
may be repeated until the desired operating pressure 
is obtained. In operation, each cycle required ap¬ 
proximately 5 min and raised the pressure of the 
system 20 psi when there was no draft other than 
convection. Hence, an operating pressure of 60 to 
65 lh could he obtained with 3 cycles in 15 min. If 
a breeze was caused to blow upon the apparatus, as 
from a small fan, two cycles were sufficient to raise 
the pressure to 57 psi in a total elapsed time of 11 
min. 

Still other changes were made. Another layer of 
evaporating coil was added, increasing the length to 
approximately 80 ft. thus increasing the evaporative 
rate approximately 50%. The auxiliary reservoir for 
pressure build-up was connected into the converter 
system with check valves so that the only operation 
to be performed during pressure build-up is the open¬ 
ing and closing of the atmospheric vent valve; this 


simplifies the pressure build-up operation, further 
reducing the time required for obtaining operating 
pressure and furthermore making it possible to in¬ 
crease operating pressure even while the converter 
is in use. 

13.7 TYPE 4—gas phase pressurized 
LIQUID OXYGEN VAPORIZER 

In the vaporizers described so far, the gas pressure 
in the system is obtained by raising the boiling point 
of the liquid phase to the desired operating pressure. 
This necessitated the introduction of a relatively 
large amount of heat to increase the boiling point 
from atmospheric pressure to a desired operating 
pressure in the neighborhood of 65 psi. The intro¬ 
duction of this large amount of heat can be avoided 
if a small portion of the liquid is vaporized to gas 
and introduced in the gas phase above the liquid. In 
practice, a thin layer of liquid at the surface can be 
warmed to the desired boiling point and remain dis¬ 
tinct from the main body of the liquid because of a 
considerable decrease in density with increased tem¬ 
perature. Little experience has been achieved on the 
effect of vibration and sloshing, or other action on 
the destruction of this warm layer. 

The operation of a successful system employing 
this principle depends upon the gravity feed of liquid 
to a vaporizing coil. A system 3 wherein a standard 
Dewar container is utilized in the inverted position, 
neck down, is illustrated in Figure 7. Further modi¬ 
fication 11 utilizes a special Dewar container provided 
with a liquid drain connection in the form of a low 
thermally conducting spiral tube within the vacuum 
housing. This system is illustrated diagrammaticallv 
in Figure 10 and the apparatus is pictured in Fig¬ 
ures 11 and 12. 

Referring to Figure 10. a Dewar flask, B, is filled 
with liquid oxygen at approximately atmospheric 
pressure. When valve F is opened, the following 
action takes place to pressurize the system automati¬ 
cally to the desired operating pressure. Liquid flows 
from the bottom of container B into pressure evapo¬ 
rator coil A T where it is vaporized and the gaseous 
oxygen is further warmed by a continuation of this 
coil N in the upper part of the apparatus. The 
warmed oxygen is then passed into the container B 

d Experimental models were constructed and tested by 
W. A. Wildhack, National Bureau of Standards. NDRC 
sponsored a production model, 20 described and illustrated 
here. 





TYPE 4—GAS PHASE PRESSURIZED LIQUID OXYGEN VAPORIZER 


305 


above the liquid C where a small portion is recon- 
densed on the surface of the liquid, thus producing 
a warm layer. Within a short period of time, this 
warm upper layer reaches a temperature at which 
the boiling point is equal to the desired operating 
pressure, whereupon a pressure-controlled valve H 
closes, preventing further flow and evaporation of 
liquid. When the system is under operating pressure, 
valve K may be opened, whereupon liquid flows from 
the bottom of the flask B into a check valve to the 
main evaporator coil where it is then vaporized and 
warmed to approximately ambient temperature. 



Figure 10. Diagram of type 4 gas phase oxygen vapor¬ 
izer. 


If, however, the pressure in the system greatly 
exceeds the set operating pressure, a pressure con¬ 
trolled by-pass valve H will open, permitting with¬ 
drawal of gaseous oxygen from the container B, until 
the pressure of the system falls to the desired oper¬ 
ating pressure. This operating pressure is deter¬ 
mined by the setting of the pressure-controlled valves 
H and H'. 

The operation of this automatic pressurizing sys¬ 
tem is dependent first upon adequate flow of liquid 
oxygen through the pressurizing circuit under the low 
hydrostatic head of the liquid oxygen in container 
B and, secondly, upon the maintenance of a relatively 
thin warm layer of liquid oxygen to prevent con¬ 
densation of oxygen in excess of that supplied by the 
pressure evaporator system. 

The apparatus, as constructed, is designed to oper¬ 
ate in the normally upright position and in an in¬ 
verted position. To provide for the inverted opera¬ 
tion, the pressurizing coil is made in two parts, A 
and N', so that one or the other will operate with the 


hydrostatic head of liquid in one or the other posi¬ 
tions. The safety valve L and the connection to the 
main evaporator coil are controlled by gravity-oper¬ 
ated valves M and M' in order that the functional 
parts of the system will be properly connected to the 
liquid or gas phase. For example, in the upright 
position, gravity-operated valve M' connects pressure 
relief valve L and pressure gauge J to the neck of 
container B (gas phase). In this position, gravity- 
operated valve M is closed so that withdrawal of gas 




Figure 12. Details of type 4 gas phase oxygen vapor¬ 
izer. 





























































306 


LIQUID OXYGEN VAPORIZERS 


through the main evaporator coil will be determined 
by the pressure-controlled valve H. Now, when the 
apparatus is inverted, valve M changes connection of 
pressure relief valve L to what formerly was the bot¬ 
tom of the container B, but which now connects 
directly with the gas phase. Valve M is now open in 
order that liquid may flow directly to the main evapo¬ 
rator coil. During operation in the inverted position, 
the automatic pressure-control valve H does not func¬ 
tion ; however, the small evaporation loss is negligible 
over the periods in which the apparatus will be oper¬ 
ated in the inverted position. 

In the experimental unit shown in Figures 11 and 
12, a pressure buildup apparatus similar to that 
described for the model immediately preceding, is 
also included in order to permit experimental evalua¬ 
tion of the two systems. 

i3.8 PORTABLE OR WALK-AROUND 
VAPORIZER 

In order to provide large aircraft with walk-around 
units which would not be dependent upon high pres¬ 
sure gas lines for recharging and which furthermore 
would have a higher oxygen capacity than was gen¬ 
erally available, a walk-around unit using liquid oxy¬ 
gen was developed. Two types of apparatus differing 
somewhat in principle and method of operation were 
developed. 

Type A, shown schematically in Figure 13, in¬ 
cludes a Dewar container B of 1-1 capacity, measur¬ 
ing approximately 6 in. in diameter and 12 in. high, 
provided with a closure at the top of the neck through 
which passes a tube 0 extending to the bottom. A 
second connection is made to the gas phase above the 
liquid C, directly into the closure. Both the gas phase 
and the liquid phase connections go to a three-way 
gravity-operated valve M so constructed that a take¬ 
off connection from the valve is at all times con¬ 
nected with the gas phase in the container, regardless 
of whether the flask is in an upright or an inverted 
position. This valve connects with a length of copper 
tubing E designed to warm the gas. A diluter de¬ 
mand regulator P, a pressure relief valve L, and a 
pressure gauge J are connected to the outlet of this 
warming coil. Filling connections D and G are also 
provided. In operation the apparatus is inverted, 
whereupon there is a rapid introduction of heat 
through the neck of the flask raising the pressure in 
the system. This pressure persists when the flask is 
again righted. A standard demand type mask is con¬ 


nected to the regulator at K. As oxygen is withdrawn 
through the regulator, it is constantly replenished 
by boiling of the liquid in the container, which in 
time serves to reduce the pressure in the system. 
When the pressure is reduced below a certain mini¬ 
mum, as evidenced by resistance to breathing or by 
falling of the pressure gauge, the apparatus may again 
be inverted for a short period during which the pres¬ 
sure is again built up. Because of the operation of the 
three-way gravity valve, it is possible to withdraw 
oxygen for breathing during this pressure build-up 
period. 

G D 



Such apparatus, charged with 1 1 of liquid oxygen 
and equipped with standard available regulators 
operating in the pressure range of 50 psi to 150 psi 
























































PORTABLE OR WALK-AROUND VAPORIZER 


307 


may be used under normal conditions of diluter 
operation for a period of 15 to 45 min before it will 
again be necessary to invert the apparatus for pres¬ 
suring. If the apparatus is stored for some hours 
before use, the pressure will slowly increase to the 
pop-off value and will be immediately available for 
use when connected. 

Experimental apparatus of this type weighs ap¬ 
proximately 5 lb empty, can be charged with 2 l / A lb 
of liquid oxygen, which is sufficient to yield 800 1 of 
gas STP. 

Type B, a later form of the apparatus, is shown in 
Figures 14 and 15. The controls and method of 
operation of this form is quite similar to the 25-1 


G D 



vaporizer described above under type 3. Liquid oxy¬ 
gen is withdrawn through a tube 0 into a coil E and 
thence to a diluter demand regulator P. A pressure- 
controlled by-pass valve H insures operation at a 
constant pressure. A gravity-operated valve M closes 
this by-pass when the apparatus is inverted. During 
periods of operation in the inverted position, gas is 
withdrawn directly from the gas phase of the liquid 
and no vaporization of liquid takes place in the 
evaporator coil, although additional heat is supplied 
to the liquid through the neck of the container. A 
pressure relief valve L and pressure gauge / is con¬ 
nected to the withdrawal line serving the diluter 
demand regulator P and is always in direct connec¬ 
tion with the gas phase of the container when the 
pressure of the system is in excess of the minimum 
operating pressure. 



Figure 15. Details of portable converter. 


Filling connection D and vent valve G is provided 
at the top. A carrying handle encloses a spring scale 
for indicating contents of liquid oxygen. 

A one-stage diluter demand regulator operating 
with a head pressure of between 9 and 25 psi was 
available in experimental form (The Aro Equipment 
Corporation, Cleveland, Ohio). In the experimental 
models produced, the pressure-controlled by-pass was 
set to open at pressures above 15 psi so that this 
pressure became the minimum operating pressure. 
The pressure relief valve was set at 25 to 30 psi. 


Figure 14. Diagram of portable converter, type B. 



































































































308 


LIQUID OXYGEN VAPORIZERS 


These valves may be readily altered to suit the oper¬ 
ating characteristics of the demand regulator used. 


Physical Characteristics 

^ 2 -Liter Size 

1-Liter Size 

Height 

12.5 in. 

14.5 in. 

Overall diameter 

5.5 in. 

6.2 in. 

Weight empty 

4.91b 

5.41b 

Weight full 

6.1 lb 

7.71b 

Weight of liquid oxygen 

1.21b 

2.31b 

Available gaseous oxygen 

375 1 

764 1 STP 

Operating pressure 

15 to 17 psi 

15 to 17 psi 


A vaporization loss in the 1-1 size, resulting from 
heat leak when the converter is not used, is at a rate 
of 0.915 lb of liquid oxygen or 40% total capacity 
per 24 hr. Oxygen delivery from the apparatus 
appeared to be adequate for diluter demand operation 
although maximum flows at sea level with no dilution 
tended to freeze the regulator and impair its opera¬ 
tion. Approximately 6 ft of % 6 -in. copper or alumi¬ 
num tubing was used for the coil. If greater delivery 
rates are desired, this coil length and diameter can 
be increased. The l / 2 -\ size is pictured in Figures 
7 and 8 as being recharged from the 25-1 converter. 

Some attention was given to gun-fire hazard of 
liquid oxygen containers of the spherical Dewar type. 
Twenty-five-liter containers, when hit squarely by 50 
caliber API, exploded or came apart in such a fashion 
as to scatter large pieces of the container. Prelim¬ 
inary tests indicated that this could be prevented by 
lacing with steel wire or cable. 19 However, much 


work still remains to be done in order to estimate 
the minimum requirements and the hazards of scat¬ 
tering the liquid oxygen contents in the fuselage of 
a plane. 

13.9 RECOMMENDATIONS FOR 
FUTURE RESEARCH 

The models of liquid oxygen vaporizers con¬ 
structed and reported herein should be given tests 
under flight conditions to estimate not only their 
operating characteristics but to gain a clear insight 
into such apparatus under flight conditions. It is 
believed that the apparatus might be considerably 
simplified (in the case of the 25-1 size) by removing 
the requirement for operation in inverted position. 
Some effort was made to obtain 1-liter containers of 
stainless steel or aluminum which would be much 
lighter and stronger than the standard copper con¬ 
tainers available. This investigation should be con¬ 
tinued as well as a study of modifications of shape 
and arrangement of apparatus to provide greater 
compactness. As already pointed out by the Army 
Air Forces, the use of portable 1-1 converters and 
means for recharging aboard aircraft may result in 
the elimination of the standard oxygen installation 
on the larger aircraft, with the elimination of con¬ 
siderable weight of equipment, decreased hazard 
from gun fire and increased flexibility of operation. 





Chapter 14 


INSTRUMENTS FOR TESTING OXYGEN 


By S. S. Prentiss a 


14 1 INTRODUCTION 

I n order to meet the requirements for special field 
testing apparatus and instruments for field equip¬ 
ment, the following instruments were developed. 

1. Instrument for determining the partial pres¬ 
sure of oxygen in a mixture of gases. 

2. Instrument for determining the moisture-con- 
tent of gases (2 methods). 

3. Instrument for determining a combination of 
properties of compressed oxygen gas. 

4. Thermometer covering a large range of low 
temperature. 

5. A dial-type liquid level gauge. 

Considerable need existed for methods of deter¬ 
mining the concentration of oxygen in a mixture of 
gases which would facilitate the rapid analyses of 
breathing atmospheres, purity of oxygen production, 
and presence of hazardous concentrations of oxygen 
in combustible gases. The Pauling oxygen meter, an 
ingenious device for measuring the paramagnetic 
properties of gases (amongst which oxygen is unique) 
proved so successful in determining the partial pres¬ 
sure of oxygen in gas mixtures that a great number 
of modifications have been developed in order to 
meet the requirements of specific problems. This 
instrument has enormously simplified analysis of ex¬ 
perimental gas mixtures in the study of breathing 
and has simplified the construction of warning and 
indicating devices for submarines, aircraft, and gas 
generating plants. The apparatus and some of the 
modifications will be described below. 

The moisture content of aviation oxygen is critical 
at 0.020 mg per 1 STP, or a frost point of —57 C. 
Oxygen that contains moisture in excess of this value 
was deemed likely to freeze oxygen equipment on air¬ 
craft because of the low temperatures at high altitudes, 
thus introducing hazards of anoxia. Oxygen, as com¬ 
mercially produced, normally has a moisture content 
much lower than this critical value; however, it 
appeared desirable to test every cylinder of com¬ 
pressed oxygen intended for aircraft use, because of 

“Technical Aide, Division 11, NDRC. 


the possible presence of water in the cylinder prior to 
filling. 

The National Bureau of Standards developed ap¬ 
paratus for determining, with considerable accuracy 
and convenience, moisture content of gases by meas¬ 
uring the electrical conductivity of a thin film of 
phosphoric acid in contact with a gas sample under 
pressure. 20 ’ 21 ’ 22 Production models of this instru¬ 
ment were made available by several manufacturers, 
for example, the American Instrument Company. 
NDRC undertook to develop apparatus which, 
though somewhat less accurate, would be more com¬ 
pact, rugged, and more suited in field use, and for a 
rough and ready determination of moisture content 
at ambient pressure. The first method devised, based 
upon induced color change in chemicals of a type 
related to malachite-green, was very ingenious, but 
interposed insurmountable difficulties of manufac¬ 
ture, standardization, and storage. As a second ap¬ 
proach, apparatus of the dew-point or frost-point type 
was developed. Both devices will be described in the 
following text. 

Some experience of the Services indicates the de¬ 
sirability of a portable instrument for quickly check¬ 
ing the following properties of compressed cylinder 
oxygen. 

1. Oxygen concentration. 

2. Moisture content. 

3. Carbon monoxide content. 

4. Pressure. 

A combination instrument which would make the 
desired determination and which incorporated meas¬ 
uring devices already developed was constructed. 

In the operation of oxygen-generating plants, it is 
sometimes desirable to follow closely the tempera¬ 
ture from ambient to the boiling point of oxygen in 
certain parts of the apparatus. The development of a 
suitable thermometer which could be manufactured 
without undue tedium of calibration is described. 

The operation of such portable equipment de¬ 
manded the availability of a liquid level gauge not 
subject to common shortcomings of manometers. A 
dial gauge for this use was developed. 


309 



310 


INSTRUMENTS FOR TESTING OXYGEN 


H 2 THE PAULING OXYGEN METER 
14 2 1 Introduction 

When testing oxygen supplies, following the 
operation of oxygen generating units, testing breath¬ 
ing mixtures, and conducting numerous other tests, 
the need existed for an instrument which could meas¬ 
ure and indicate the partial pressure of oxygen in a 
mixture of gases. Further advantages were to be 
obtained from a compact portable instrument that 
would give rapid and continuous determinations 
without chemical manipulations. An instrument was 
proposed for this purpose, the operation of which 
would depend on the extraordinarily high magnetic 
susceptibility of oxygen. 

Most gases are diamagnetic; that is, they tend to 
be repelled from a magnetic field. Only a very few 
gases are paramagnetic and tend to be attracted into 
a magnetic field, and of these, oxygen is the only 
common gas. It is a very important circumstance 
that the magnitude of the magnetic susceptibility of 
oxygen is many times greater than that of any other 
common gas. As an example, the volume magnetic 
susceptibility of oxygen at standard conditions, 
142 X 10‘ 9 cgs, may be compared with that of nitro¬ 
gen, —0.40 X 10~ 9 cgs, which is representative of 
the diamagnetic gases. Because of this relatively 
high susceptibility of oxygen, the susceptibility of a 
gas mixture is much more strongly influenced by a 
change in its oxygen content than by an equal change 
in any other component, and, in fact, if the oxygen 
content exceeds a few per cent the susceptibility of 
the mixture is closely proportional to the partial pres¬ 
sure of oxygen. 

The forces produced by the action of magnetic 
fields upon small volumes of gases are proportional 
to the susceptibilities of the gases and are very small. 
This is true even in the case of the most strongly 
magnetic gas, oxygen, at ordinary pressures in the 
strongest magnetic fields obtainable in the laboratory. 
The smallness of these forces gives rise to a number 
of problems which had to be considered in the de¬ 
velopment of the oxygen meter. 

The condition of equilibrium is determined by the 
following equation: 

K6 = H^L (K t -K m ) Vr (1) 

dO 

in which K is the torsion constant of the supporting 
quartz fiber and 6 is the angular displacement of the 
test body. H is tbe magnetic field strength, dH/d6 


is the angular field strength gradient, Kt is the vol¬ 
ume magnetic susceptibility of the test body, K m is 
the volume magnetic susceptibility of the surround¬ 
ing medium, and V is the volume of the test body, 
r is the effective radius. 

14 2 2 Description and Method of 
Constructing 

Experimental Models 4 

A small glass dumbbell 1.4 cm long with spheres 
4 mm in diameter is mounted upon a quartz fiber, 
8 [x in diameter, as shown in Figure 1. A small mir¬ 
ror is included in the dumbbell assembly. 



Figure 1. Completed suspension for Pauling oxygen 
meter. 


The dumbbell assembly is then mounted in a 
strong, inhomogeneous magnetic field provided by 
one or two Alnico permanent magnets, as shown in 
Figure 2. The test body, or dumbbell, with attached 
mirror is arranged to rotate through regions of vary¬ 
ing magnetic field strength by twisting and untwist¬ 
ing the fiber. 















THE PAULING OXYGEN METER 


311 




Figure 2. Assembly of magnets, pole pieces, and sus¬ 
pension. 


Method of Constructing the Suspension 1 ^ 

The steps involved in making a suspension will be 
discussed in the following order: making fibers, mak¬ 
ing forks, stringing forks with fibers, straightening 
and stretching fibers, testing mounted fibers, blow¬ 
ing bubbles, sizing bubbles, making dumbbells, testing 
dumbbells, making mirrors, assembling suspensions, 
and balancing suspensions. 

Making Fibers. The torsion fibers are made from 
clear fused quartz rods. Whatever the original size, a 
rod is first drawn out to a diameter of about 1 mm. 
Slight contamination of the quartz greatly reduces 
its strength. A single dust particle on a fine quartz 
fiber will almost always cause the fiber to burn apart in 
the flame. The torch used for blowing fibers has a 
y 16 -in. cylindrical orifice and burns a mixture of 
oxygen and natural gas. 

A fiber is drawn to a length of about 3 ft, which 
is usually 50 to 150 g in diameter. The final step is 
the reduction of the coarse fibers to fine fibers rang¬ 
ing from 3 to 10 g in diameter. For this operation 

b The methods of construction are only outlined here. 
Recourse should be had to the reference report 4 for a full 
description of exceptionally neat micro manipulations. 


the oxygen supplied to the torch is reduced until a 
flame 15 or 20 in. high with a little white at the top 
is obtained. One of the coarse fibers is heated and 
drawn vertically in this flame to the desired diameter 
of 3 to 10 g. Because of diffraction effects, fibers of 
sizes useful for suspensions appear colored when 
viewed as described. In the largest usable sizes the 
colors are very pale; in the smallest they are quite 
brilliant. 

Making Forks. The forks, or quartz yokes, on 
which the fibers are strung are made from quartz rod 
about 1 mm in diameter. The quartz rods are 
cemented into brass bushings using mixture of bake- 
lite, rosin, shellac, and a little alcohol, and then baked 
in an oven at 120 C. 

The bushing is held horizontally in a pin vise 
which may be rotated in such a manner that all bends 
may be made by the action of gravity when the rod 
is heated at the appropriate point. The form and 
dimensions of a typical fork are shown in Figure 3. 

Stringing Fibers on Forks. The operation of fusing 
the fine quartz fibers to the quartz forks must be 
carried out in a place free from dust and air cur¬ 
rents. The work is observed under the lowest power 
of a binocular microscope. A fiber of convenient 
length is selected and attached to the fork by means 
of micro manipulators after the fork tips have been 
softened with a torch flame. 



Figure 3. Method of making forks. 


Straightening and Stretching Strung Fibers. The 
purpose of these operations is to align the quartz 
fiber with the axis of the brass bushing and to put 
it under a slight tension. The strung fork which is 
to be straightened is held in a small lathe-like jig 
by clamping the bushing of the fork in a collet. This 
mounting may be rotated by a hand wheel. Opera¬ 
tions are observed with a binocular microscope. 
Various portions of the fork may then be softened 
with a torch flame and manipulated until the two 
ends of the fiber are aligned with the bushing axis 
within 0.005 cm. 


















































312 


INSTRUMENTS FOR TESTING OXYGEN 


After the strung fork has been straightened it is 
necessary to put the fiber under a slight permanent 
tension. With the fork still in the jig, the tail stock 
is brought near the end of the fork and clamped 
into place. The screw in this tail stock is then turned 
until the tip of the fork is bent 0.0025 cm toward 
the bushing (0.0037 cm for smaller fibers). The 
knob of the fork is heated until the fiber is drawn 
taut, the tail stock is withdrawn leaving the fiber 
under tension, and the mounted fiber is ready for 
testing. 

Testing of Mounted Fibers. The first test that is 
applied to strung forks is a very simple one. A suit¬ 
ably bent quartz rod weighing about 50 mg must be 
lifted by the fiber, while horizontal, at its center. The 
hook which is attached to the weight is coated with 
fused silver chloride where it touches the fiber in 
order to minimize the possibility of scratching the 
fiber. 

The determination of the relative torsion charac¬ 
teristic, or torque of the fiber is made as follows. A 
small standard size quartz rod is temporarily fas¬ 
tened by one end to the center of the fiber so that the 
rod hangs vertically when the fiber is horizontal and 
untwisted. The angle through which the fork must 
be rotated in order to cause the attached rod to 
deviate from the vertical by a standard angle is then 
read from the dial of the spindle which holds the 
bushing. The difference between the measured angle 
and the standard angle is called the torque of the 
fiber; it is inversely proportional to the torsion con¬ 
stant of the fiber. 

The quartz rod which is used for this test is speci¬ 
fied quite arbitrarily, to be 3 mm long and 0.100 mm 
in diameter. The standard angle to which the rod is 
made to deviate from the vertical is 58 degrees. 

Blowing Bubbles. It is very desirable that the 
glass bubbles which are to he used for making the 
small rotating test body (the dumbbell) be made to 
conform to certain specifications. They must be held 
to reasonable tolerances of shape, size, and weight. 
They should be as light as possible and still suffi¬ 
ciently strong to withstand pressure differences of 
an atmosphere or more between inside and outside. 
It is often desired that they possess certain magnetic 
properties. 

These bubbles are about three mm in diameter. 
With the short stem that is left on them to form half 
of the dumbbell cross bar, they weigh about 0.7 mg 
each. 

It has been found that these small bubbles can be 


blown more easily from laboratory soft glass than 
from pyrex glass. A piece of soft glass tubing is 
first drawn out into a thin-walled capillary 0.5 mm 
in diameter. A natural gas flame about in. high 
and containing little or no primary air (air intro¬ 
duced at the base of the burner) is used. The tip of 
the capillary tube is inserted into the flame and 
melted to form an extremely small ball of glass on 
the end of it. The tube is jerked axially from the 
flame and almost simultaneously is blown with a 
quick puff of air from the mouth to form a bubble. 
The timing of this manipulation must be accurate 
and is attained only with practice. The blowing is 
done with the lips and the tongue in order to obtain 
the quickest and most powerful puff of air. The 
oversize, aspherical bubble is then shrunk to the 
correct size and to a spherical shape by rotating it 
well above the small Bunsen flame. 

The above procedure is probably the most diffi¬ 
cult of the procedures involved in making a Pauling 
oxygen meter. However, with practice a good 
manipulator can learn to blow acceptable bubbles at 
an average rate of one or two dozen per hour. Since 
only two are required for each meter, exclusive of 
breakage, the time required to produce bubbles is 
not disproportionately large. 

A new improvement in the manufacture of bubbles 
which considerably lessens the required degree of 
skill has been developed by the A. O. Beckman 
Laboratory. A spring-operated valve device simul¬ 
taneously blows out the gas flame and introduces 
into the capillary tube the correct quantity of air. 
The bubbles so obtained are shrunk to the desired 
size and shape by the procedure described above. 

For special purposes it is sometimes desired to 
obtain dumbbells with a higher paramagnetic suscep¬ 
tibility than can be obtained from soda glass bubbles 
filled with oxygen. One way of obtaining such dumb¬ 
bells is to make them of bubbles made of paramag¬ 
netic glasses. Glasses containing iron, for example, 
may exhibit a positive net susceptibility; special 
glasses containing iron might be made up. For ex¬ 
perimental work it was found to he more convenient 
to test the magnetic properties of a number of sam¬ 
ples of glass and to keep these tested samples on hand 
than to make up special glasses. Old green-glass 
champagne bottles were found to give a great variety 
of magnetic susceptibilities. 

Sizing Bubbles. When a hatch of bubbles has been 
prepared the bubbles must be sorted according to 
size. This sorting involves a volume determination 




THE PAULING OXYGEN METER 


313 


which is carried out by weighing the bubbles first in 
air and then immersed in alcohol. For this purpose 
a very sinple type of quartz fiber balance is used. 

Making Dumbbells. The three parts of a dumb¬ 
bell are the two bubbles, matched in size, and a bal¬ 
ancing rod. The magnetic properties desired for the 
dumbbell determine the kind of glass which must be 
used for the bubbles and the composition of the gas 
which must be sealed into the bubbles. A commonly 
used dumbbell is made of ordinary soft glass hubbies 
filled with air. If some other gas is to be used to fill 
the dumbbells, the bubbles are placed in a vacuum 
desiccator. The desiccator is evacuated and the fill¬ 
ing gas is admitted up to atmospheric pressure. The 
ends of the bubble stems are then sealed with a small 
torch as quickly as possible after opening the desic¬ 
cator. The bubble stems are cut off with the 0.008-in. 
torch to give an overall length of 4.5 mm for the 
bubble and stem. The balancing rod material is a 
coarse glass fiber, about 0.1 mm in diameter, usually 
drawn from a magnetically neutral soft glass. The 
two hubbies and the balancing rod are held in sepa¬ 
rate holders; at least two of these holders are at¬ 
tached to micro manipulators. 

Alignment of the bubbles and balancing rod prior 
to sealing them together should be done with the 
greatest possible accuracy. The object of careful 
alignment is to make the dumbbell such that when 
it is assembled in a suspension the fiber will pass 
very near to the center of volume of the combination 
of the dumbbell and the mirror (which may be re¬ 
ferred to collectively as the dumbbell). Gravitational 
balance can be perfected after the suspension is as¬ 
sembled. 

Meters having suspensions in which the center of 
volume does not fall quite close to the fiber will ex¬ 
hibit an undesirable buoyancy effect when used in 
gases having densities different from atmospheric air. 
The actual fusing or sealing is done by bringing the 
0.008-in. torch, its flame held vertical, from the 
operator toward the junction. The dumbbell is 
dropped immediately into a bottle of alcohol. 

Testing Dumbbells. Before dumbbells are removed 
from the bottle of alcohol into which they have been 
dropped, they are tested for strength and for leaks. 
Suction is applied to the mouth of the bottle until 
the pressure is reduced to about the vapor pressure 
of alcohol, taking care that the alcohol is not per¬ 
mitted to boil violently. It is also desirable to test 
the dumbbells against external pressure. In a nor¬ 
mal test compressed air at 10 or 15 psi would be 


applied; however, for special meters it might be 
desirable to select dumbbells that would withstand 
greater pressures. Under these treatments weak 
bubbles burst or collapse and leaky bubbles fill with 
alcohol and submerge. The dumbbells which have 
been unaffected by these tests are rinsed with fresh 
alcohol and are ready for further operations. 

Before using the dumbbells in making completed 
suspensions it is often desirable, although not always 
necessary, to determine their magnetic properties, as 
these may influence the choice of values of the other 
parameters of the suspension. This is done by assem¬ 
bling and roughly balancing a temporary suspension 
using a dumbbell to be tested and a fiber which is 
repeatedly used for this purpose. This suspension is 
placed between a pair of pole-pieces which are at¬ 
tached to an electromagnet. In general, the passage 
of current through the electromagnet will cause a 
deflection of the dumbbell. The partial pressure of 
oxygen which reduces the deflection of the dumb¬ 
bell to zero is equivalent to the average volume mag¬ 
netic susceptibility of the dumbbell, expressed in units 
of oxygen partial pressure, at the position of the 
field occupied by the dumbbell, and at the tempera¬ 
ture at which the experiment is conducted. 

Making Mirrors. The small mirrors used in the 
suspensions are about Yr, in. square and about 0.003 
in. thick. They should be made as thin as possible 
without being too fragile. Glass, fused quartz, and 
crystal quartz have all been used. Fused quartz is 
particularly desirable because its low coefficient of 
thermal expansion prevents it from cracking under 
the influence of the high temperature gradients which 
are present during the process of sealing the dumb¬ 
bell, fiber, and mirror together. 

The small squares of glass or quartz are thoroughly 
cleaned and dried. They are then given a metallic 
coating by evaporation of metal onto them in a high- 
vacuum chamber. Aluminum is not very satisfactory 
because it reacts with the silver chloride which is 
used in cementing the suspension together. Pal¬ 
ladium is satisfactory in this respect; it also has the 
advantage of being paramagnetic while quartz and 
glass are diamagnetic so that mirrors can be made 
that are approximately magnetically neutral. 

Assembling Suspension. The brass bushing on the 
fork is held in a collet in the spindle of a jig. The 
dumbbell is fastened with paraffin to a holder which 
can be moved horizontally by two screws, one pro¬ 
ducing movement parallel to the axis of the spindle 
and the other producing movement perpendicular to 



314 


INSTRUMENTS FOR TESTING OXYGEN 


it. The mirror is held on a flat silver plate (to give 
good heat conduction) at the end of a brass rod. The 
work is observed under a microscope. 

After the parts have been fastened to their hold¬ 
ers they must be brought together into the correct 
positions for sealing together. Sealing is done with 
fused silver chloride. 

The angles between the fork and the dumbbell, 
between the mirror and the dumbbell, and between 
the mirror and the fiber depend upon the optical 
system and mechanical arrangements of the model of 
the oxygen meter for which the suspension is being 
made, and upon the particular range which is de¬ 
sired. The required fiber torsion constant and the 
required dumbbell susceptibility depend upon the 
characteristics of the magnetic field in the particular 
model and upon the particular range which is desired. 
The dumbbell must often be further selected on the 
basis of its temperature coefficient of volume mag¬ 
netic susceptibility if it is to he used in a temperature- 
compensated instrument. 

Balancing Suspensions. For testing balance, a 
suspension is shielded completely from air currents 
by a transparent celluloid cover which fits over the 
spindle of the assembly jig and rotates with it. On 
the flat closed end of this cylinder are engraved a 
set of parallel lines which are useful in observing 
relative motions of the dumbbell and the fork. The 
ultimate criterion for perfect balance is the lack of 
any change in the relative positions of the dumbbell 
and the lines on the cap when the spindle is rotated 
through 360 degrees. 

Coarse balancing is accomplished by adding very 
minute droplets of a low melting lead borate glass to 
the appropriate place on the dumbell. Powdered lead 
borate is picked up. melted, and applied with the 
0.002 in. platinum hot wire. 

Fine balancing is accomplished by evaporating 
traces of silver chloride or iodide or a mixture of the 
two from a platinum hot wire (0.01 in. in diameter) 
onto the dumbbell. 

The dumbbell must be balanced in all planes which 
include the quartz fiber. It will he so balanced, how¬ 
ever, if it is balanced in any two of them. 

The Completed Suspension. A completed suspen¬ 
sion is shown in Figure 4. 

The Magnet and Pole Pieces 

The permanent magnets are made of Alnico V. 
It is customary to use a pair of symmetrically placed 
magnets weighing about 5 oz each giving maximum 


effective field strength of about 5,000 oersteds. How¬ 
ever, a sensitive meter has been designed and built 
using a single magnet weighing about 6 lb (Model 
K). 



Various shapes of pole pieces have been tried. A 
suitable shape must not only be satisfactory magneti¬ 
cally but must also meet certain requirements im¬ 
posed by the attached mechanical and optical sys¬ 
tems. Three types of pole pieces have been found 
satisfactory and useful in different applications. 
These three types are illustrated in Figures 2, 5, and 
6. The first two types have been used with the 
smaller magnets and seem to be roughly equivalent 
from the standpoint of field characteristics; mechani¬ 
cal considerations have dictated the choice between 
these two types for different applications. Figure 6 
shows the type of pole piece used with the large mag¬ 
net mentioned above (Model K). 

A magnetizer was built according to a design de¬ 
veloped in the Bell Telephone Laboratories. 27 This 
was used to magnetize the large magnets which are 
used in the Model K meters. Figure 7 is a schematic 
circuit diagram of the magnetizer. A battery of elec¬ 
trolytic condensers, of total capacity 2,600 /ffd, is 
charged to about 350 volts by means of a transformer 
and rectifier and is discharged through the magnetiz- 













315 


THE PAULING OXYGEN METER 


ing coil (six turns of Xo. 8 copper wire) around the 



Figure 5. Pole pieces and backplate—Model P. Mag¬ 
nets removed. 



LOWER POLE PIECE WITH 
SUSPENSION 

Figure 6. Model K: Magnet and test chamber, with 
pole pieces and suspension. Window, cover and rubber 
gasket removed. 






































































316 


INSTRUMENTS FOR TESTING OXYGEN 


The Optical System, Flow Control, and 
Temperature Correction 

The test body and magnet are mounted in a cabi¬ 
net together with suitable devices for controlling the 
flow of sample gas and for observing the deflection 
of the test body. 

The flow to the sample chamber may be controlled 
by a needle valve and flow meter of the “Rotameter” 
type (as in Model P) or by a sensitive pressure regu¬ 
lator (plenum chamber) and orifice (as in the com¬ 
bined Bureau of Standards moisture indicator and 
oxygen analyzer). In later models 7 the gas sample 
flows through a passage-way which connects with 
the sample chamber through a porous diffusion disk. 
This last method has the advantage that the read¬ 
ing is independent of flow over a considerable range 
of flows and the test body suspension is not subject 
to injury by high flow rates. It has the disadvantage 
that an appreciable time (45 to 60 sec) is required 
to established equilibrium through the diffusion disk. 

The test body suspension and magnet poles are 
enclosed in a gas-tight chamber with entrance and 
exit ports for the gas sample. A lens window in this 
chamber forms part of the optical system in which 
the image of a lamp filament is focused upon the 
mirror on the suspension and thence to a scale gradu¬ 
ated in millimeters of partial pressure or per cent of 
atmosphere, as desired. 

The fact that the magnetic susceptibilities of both 
oxygen gas and the dumbbell depend on the tem¬ 
perature implies a temperature effect on the reading 
of the meter. Three methods of making the oxygen 
meter usable at different ambient temperatures have 
been used. The most direct method is to make cali¬ 
brations at various temperatures and to provide cor¬ 
rection tables or graphs. Another method involves 
compensating the meter for temperature effects. To 
do this, the magnetic field strength is caused to vary 
with temperature in such a manner as to counteract 
the temperature dependence of the susceptibility of 
oxygen. It is also necessary to use a dumbbell which 
has the same temperature behavior as has the sur¬ 
rounding gas. The desired variation in field strength 
is obtained by placing across the permanent magnet 
a shunt made from one of those iron-nickel alloys 
which have very high temperature coefficients of 
permeability at ordinary temperatures. The third 
method of eliminating the temperature effects is to 
maintain the meter at a constant temperature by 
means of a thermostat. 


14 2 3 Deflection-Type Instruments 

Developed at California Institute 
of Technology 

Early Models. The first complete oxygen meter, 
other than the purely experimental laboratory ap¬ 
paratus, was the one known as Model A. c This was 
calibrated to cover a range of 0 to 160 mm of oxygen. 

The next six meters constructed were designated 
as Model B. Model C, which included two meters 
very similar in appearance to Model B, differed from 
B chiefly in having two magnets instead of one. Both 
Model B and Model C were equipped with a by-pass 
valve so that the flow of sample could be cut off 
while a reading was being taken. 

The Model P Pauling Oxygen Meter. The next 
model developed after Model C was Model P, a 
fairly rugged laboratory instrument. About thirty of 
them were constructed at the California Institute of 
Technology and sold for various war purposes.* 1 

One of these meters is shown in Figure 8. The 
walnut veneer cabinet has dimensions of about 7x 
7x12 in. The total weight of the meter is about 12 lb. 
On the black bakelite front panel of the instrument 
may lie seen the calibrated oxygen partial pressure 
scale, the thermometer scale, the power switch, the 
needle valve control handle, the Rotameter flow indi¬ 
cator, and the nipples by means of which the gas to 
be analyzed is caused to flow through the meter. 

The A. O. Beckman Laboratories took over the 
manufacture of Model P meters in the summer of 
1942. This model is not being currently produced; 
it has been superseded by models which have been 
more recently developed by this concern. 

Model D, the “Submarine Model.” A promising 
application of the oxygen meter is its use in meas¬ 
uring the oxygen content of the ambient air in a 
submarine to determine its respirability. For this 
purpose a meter, designated as Model D, was de¬ 
signed and constructed. It differs from Model P 
primarily in that the gas sample enters the analysis 
chamber by diffusion and convection, direct from 
the surrounding atmosphere. The test chamber is 
electrically heated in order to keep it above the 
ambient temperature of the submarine and thereby 

Dr. A. O. Beckman and his associates are currently 
producing a Pauling oxygen meter which they designate as 
“Model A” and which should not be confused with the one 
here described. 

rt Most of the developmental cost and all of the construction 
costs of these Model P meters were provided by funds other 
than those available under NDRC contracts. 




THE PAULING OXYGEN METER 


317 



£ 


Figure 8. Model P Pauling oxygen meter. 


prevent condensation of water in the meter when it 
is used in atmosphere of high relative humidity. This 
heating also promotes convection and improves the 
gas circulation, thereby reducing the time required 
for the meter to register a change in the oxygen con¬ 
tent of the ambient atmosphere. The optical system 
is similar to that of Model P but utilizes an illumi¬ 
nated slit as a light source. 

Model L, the “Airplane Model.” A possible appli¬ 
cation of the oxygen meter is its use in airplanes to 
test oxygen equipment used in high-altitude flying. 
A meter which is to be used for this purpose should 
he compact, light in weight, ruggedly constructed, 
well protected against vibration, and operable over 
a wide temperature range. An experiment was car¬ 
ried out in which two Model P oxygen meters were 
carried to an altitude of 30,000 ft in a Liberator 
bomber and tested in flight. Both meters performed 
quite satisfactorily. However, the size, weight, and 
construction of the Model P meter, which is essen¬ 
tially a laboratory instrument, are not especially 
favorable for continued use in a flying airplane. 

A meter, designated as Model L, has been devel¬ 


oped specifically for such use. The cabinet and most 
of the parts are of aluminum, for considerations of 
weight; the entire instrument weighs less than 5 lb. 
The meter is very compact; the overall dimensions 
are 3^4x6^4x8 in. 

The test chamber and magnet assembly, the 
shield frame, the scale support, and the optical sys¬ 
tem form a rigid unit which is mounted, by means 
of Lord double-rubber mountings which protect it 
against vibration and shock. 

The Model K Oxygen Meter. With the aid of the 
Bell Telephone Laboratories a magnetic circuit has 
been designed which employs a magnet of Alnico V 
weighing about 6 lb, and a suitably designed test 
chamber (Figure 6). The magnet was remagnetized, 
with the test chamber in place. A maximum field 
strength of about 11,000 oersteds was measured be¬ 
tween the pole pieces. Since the magnetic forces act¬ 
ing upon the dumbbell vary with the square of the 
maximum field strength for a given field shape, these 
magnetic forces should be four or five times as great 
as in other models, permitting increase by a factor of 
the order of four or five in the torsion constant of the 










318 


INSTRUMENTS FOR TESTING OXYGEN 


fiber. One model of the oxygen meter Model K em¬ 
ploying such a magnet and test chamber has been 
developed. 

Because of the inconvenience of winding a mag¬ 
netizing coil on the magnet with the test chamber in 
place, and because of the necessity for remagnetiza¬ 
tion after every occasion of removing the test chamber 
or a pole piece, it would he desirable to provide a 
means of installing and adjusting the suspension in 
the test chamber without first removing the test 
chamber or either pole piece from the magnetic 
circuit. 

14 2 4 Deflection-Type Instruments 

Developed by the A. O. Beckman 
Company 7 

Model P. The Model P instrument is described 
in detail in the preceding section. 

Many of the instruments had temperature com¬ 
pensators, consisting of a magnetic shunt made from 
an alloy with a high negative temperature coefficient 
of magnetic permeability at ordinary temperatures. 
Approximately 30 instruments of this type were made 
at the California Institute of Technology and 94 in¬ 
struments were made by the Arnold O. Beckman 
Company. As the attempt to achieve temperature 
compensation by the magnetic shunt was not very 
successful, in many of the later instruments the tem¬ 
perature compensator was replaced by a thermo- 
switch and an electric heater which maintained the 
analysis cell at constant temperature. 

The Model P instrument was made in various 
ranges, including the following: 0-35 nun, 0-160 
nun, 0 - 200 mm, 0 - 250 mm, 0 - 400 nun, 0 - 500 
nun, 0 - 600 mm, 0 - 800 mm, 650 - 760 nun, and 
580 - 800 nun. 

Model S. This model, like the Model D, was de¬ 
signed specifically for use in submarines or other 
enclosed spaces where it is desired to analyze the 
ambient air. The internal construction of the instru¬ 
ment is essentially similar to that of the thermostated 
Model P instrument. The needle valve and flow 
meter are omitted. Sampling of the ambient air is 
obtained by diffusion and thermosyphon action. The 
temperature of the analysis cell is held constant at 
approximately 140 F. The inlet and exit connections 
to the analysis cell are protected by a glass-wool 
dust filter and magnetic filters to remove any mag¬ 
netic particles which might be present. 

The completed instrument is boused in a steel case 


6j/2x7x4j/2 in. The internal assembly is protected 
from shock damage by mounting on rubber shock 
mountings. The instrument successfully passed the 
standard Navy vibration and shock tests. 28 

Model A. The Model A instrument is a portable 
laboratory instrument for general use where readings 
in oxygen partial pressure units are desired. A con¬ 
stant temperature analysis cell having cylindrical 
glass walls is used. No needle valve or flow meter is 
included, as the instrument is designed to accom¬ 
modate widely varying flow rates through the use of 
restricting orifices and a built-in by-pass device 
which automatically by-passes part of this sample 
stream whenever this rate of flow is excessive. The 
instrument is housed in a walnut carrying case 
714x7 in. 

Model T. A small meter, Model T, weighing but 
2/ 2 lb, and measuring 5x2 l / 2 x6 in., was developed 
for testing the atmosphere of oxygen tents and other 
therapeutic apparatus. Gas samples are drawn into 
the test chamber through small diameter rubber tub¬ 
ing by means of a rubber bulb. An additional mirror 
has been inserted in the light path to increase its 
length. Bv reason of the lengthened optical path, the 
total angular rotation in Model T is only 8 degrees, 
compared to 30 degrees in Model A. It has been 
found possible under these conditions to reproduce 
component parts so nearly uniform that individually 
calibrated scales are not required. 

14 2 5 Null-Type, Electrostatically 

Balanced Instruments Developed 
at Arnold O. Beckman 
Company 

Electrostatic Balance 

The deflection-type instruments are particularly 
suited for applications where oxygen partial pressure 
readings are required. In many cases readings in 
oxygen percentage are desired. Oxygen percentages 
can be obtained, of course, by dividing the oxygen 
partial pressure by the total pressure of the gas in 
the analysis cell, but this procedure is often very in¬ 
convenient. For industrial applications, where con¬ 
tinuous recording and automatic control are desired, 
means for obtaining oxygen content directly in per¬ 
centages would be very valuable. Instruments incor¬ 
porating such means were developed and are known 
as electrostatic models or null-type instruments. 

In these instruments a new force is added to the 



THE PAULING OXYGEN METER 


319 


magnetic and torsional forces involved in the deflec¬ 
tion-type instruments. By establishing an electro¬ 
static potential between the rotable test body and 
suitably placed electrodes, electrostatic forces of the 
same order of magnitude as the magnetic and me¬ 
chanical forces involved are added. This additional, 
easily adjustable parameter makes it possible to 
standardize the oxygen meter at the ambient pressure 
with some known reference gas, so that subsequent 
readings on unknown gases will be indicated directly 
in terms of oxygen percentage. The use of an elec¬ 
trical potential, furthermore, makes possible the use 
of conventional chart recorders and process control 
equipment. These instruments have proved to he 
very useful, particularly in refineries for the produc¬ 
tion of aviation gasoline and toluene. 

Electrostatic Null Method No. 1, Square Lazo. In 
the deflection-type instruments there are two forces 
affecting the rotation of the dumbbell-shaped test 
body, namely, the magnetic force and the torsional 
mechanical force of the quartz fiber. If an electro¬ 
static field is introduced in addition to the magnetic 
field, charges will be induced on the test body and 
the test body will thereby be subjected to an electro¬ 
static force. The electrostatic field can be produced 
conveniently by applying a potential between the 
magnetic pole tips. With the dimensions and geome¬ 
try of the conventional instrument, potentials of the 
order 20 to 100 volts produce electrostatic forces of 
the same order of magnitude as the magnetic forces 
involved. 

Electrostatic Null Method No. 2, Linear Relation. 
The electrical circuit of this type may he compared to 
the conventional Wheatstone bridge, in which two 
arms of the bridge are photocells. Since, with a given 
voltage, the current flowing through a photocell 
changes in relation to the amount of light falling upon 
it, the photocell may be considered to be a variable 
resistor. With a galvanometer of sufficient sensitivity 
to work with high impedance photocells, a simple 
Wheatstone circuit could be used. By the use of two 
electronic tubes in a cathode-follower arrangement, 
circuit impedances can be matched so that a conven¬ 
tional low resistance voltmeter can be used as the 
indicating instrument. 

The operation of the circuit is as follows. With 
identical phototubes equally illuminated, the 90-volt 
D-C potential will be divided equally across the two 
photocells. The grids of the two electronic tubes, 
therefore, will give the same potential, namely 45 
volts. The cathode of the tubes will also be of the 


same potentials, slightly above 45 volts, so that the 
voltmeter will read zero. Assume that the mirror 
rotates so that the lower phototube receives more 
illumination. The potential of the first grid will be 
decreased, whereas the potential of the second grid 
remains at 45 volts. Consequently, the voltmeter will 
indicate the difference of potentials between the two 
cathodes just as the galvanometer would indicate a 
difference in potential in the simple Wheatstone 
bridge circuit. 

The test body is gold-plated for electrical con¬ 
ductivity and is electrically connected through the 
quartz fiber to the first cathode. As the first cathode 
potential decreases, the potential of the test body 
likewise becomes less, thereby producing an electro¬ 
static force which tends to restore the dumbbell to its 
original position. The test body does not return 
exactly to its original position but, as in the case of 
the square law method, an angular position minutely 
different from the null position suffices to generate a 
D-C potential of the proper magnitude to balance the 
magnetic and torsional forces acting on the test body. 

The condition of static balance in the electrostatic 
instruments is defined by the equation 

kO = L m -(- L e 

= A tv, -V,r, (2) 

where L m is the magnetic torque given by the right- 
hand member of equation (1), L e is the electrostatic 
torque, A and B are the angular rate of change of 
capacity between the test body and electrodes and be¬ 
tween the electrodes, respectively, and V u V 2 , and V 3 
are the potentials on the electrodes and test body, 
respectively. 

By means of the photocells and the appropriate 
circuit connections, the variational suspension voltage 
is made proportional to the angular rotation of the 
test body and the stabilizing effect of negative feed¬ 
back is obtained. The output voltage V, measured 
between the test body and a fixed point in the circuit 
is given hy 


where L° e is a constant electrostatic torque dependent 
upon the zero setting of the instrument. 

Model R. This was the first of the electrostatic 
instruments. In these instruments the voltage be¬ 
tween the test body and the electrodes required to 
maintain the test body in its null position varies as the 





320 


INSTRUMENTS FOR TESTING OXYGEN 


square with respect to the change in oxygen partial 
pressure. Because of this square law relation, the 
Model R instruments have always been used with the 
electrodynamometer type of recording voltmeter in 
which the deflection is proportional to the square of 
the applied voltage. The combination results in an 
approximately linear percentage scale. 

Model E. In this instrument the electrical circuit 
is such that an accurately linear relation exists be¬ 
tween the null-balance voltage and the change in 
oxygen partial pressure. There are obvious advan¬ 
tages in a linear scale for calibration and standardiza¬ 
tion, as well as in use. The Model E is designed for 
laboratory use and is a multi-range instrument, hav¬ 
ing five ranges of 0 to 5%, 0 to 25%, 25 to 50%, 50 
to 75%, and 75 to 100% oxygen. Standardization 
for the ambient barometric pressure is easily made 
with the aid of dry air or other reference gas. The 
instrument is adjusted to a null balance by manual 
operation of a potentiometer dial, which is calibrated 
directly in oxygen percentage. 

Model F. In this instrument also a linear relation 
exists between voltage and change in oxygen partial 
pressure. The instrument differs from the Model E. 
however, in that manual adjustment of the balancing 
voltage is not required. Tbe test body is automati¬ 
cally maintained in null position by a self-balancing 
electronic circuit. The balancing potential is shown 
continuously on an indicating voltmeter. 

Model G. This model is substantially identical 
with the Model F except that the indicating meter 
is replaced by a potentiometer-recorder. These in¬ 
struments have been of particular interest in the low 


range, 0 to 5%, for catalyst regeneration control in 
oil refineries, and in the high range, 95 to 100%, in 
plants for the production of oxygen. 

Aircraft Model. This experimental flight model 
is an adaptation of the linear electrostatic Model F 
designed for operation from portable dry-cell bat¬ 
teries. The analysis unit, which is 5in. wide, 5^4 
in. long, in. high and which weigh 4 lb, 10 oz, 
is attached by rubber shock mountings to a battery 
case. Tbe complete instrument, including tbe bat¬ 
teries, weighs 18 lb, 8 oz. The useful life of the bat¬ 
teries is about 100-hr continuous operation. 

Oxygen partial pressure is indicated continuously 
on a microammeter built into the analyzer. Calibra¬ 
tion adjustments are as on Models E, F, G, with the 
addition of a means of suppressing the zero point any 
amount up to about 0.75 atm air. 

14 3 INSTRUMENTS FOR DETERMIN¬ 
ING MOISTURE CONTENT 
OF GASES 

14 3 1 Chemical Method 13 

A survey of chemical tests for the detection of 
water vapor was made, but none was satisfactory for 
the high sensitivity needed (the detection of 0.01 to 
0.010 mg per 1). An investigation was therefore 
made of a series of compounds of ketones and Grig- 
nard reagents which can form internal ions accom¬ 
panied by the development of intense color. This 
internal rearrangement is induced by tbe high dielec¬ 
tric properties of water. The most useful compound 
is a complex of Michler’s ketone and Grignard agent. 


(CH 3 ) 2 N 




N(CH 3 ) 2 


+ CH.Mgl 


Michler’s Ketone 


(CH 3 ) 2 N 



N(CH 3 ) 2 


OMgl 


(resonance) 



N + (CH 3 ) 2 


Colorless MeMMgl 


Colored MeMMgl 


























INSTRUMENTS FOR DETERMINING MOISTURE CONTENT OF GASES 


321 


The constitution of colorless MeMMgl has by no 
means been established, and that for the colored com¬ 
pound is purely hypothetical, based on the coloration 
of malachite green leucocyanide by light, which is 
supposed to be 


tive exposure time for coloration compared to 
MeMMgl. 

Preparation of Reagent. The Grignard reagent 
was prepared from anhydrous methylal iodide and 
magnesium turnings suspended in dibutyl ether in an 



Malachite green 
leucocyanide (colorless) 


Malachite green 
cyanide (colored) 


A related reagent which may be designated EtM- 
MgBr was made from ethyl bromide instead of 
methyl iodide. This compound is so much more 
sensitive than MeMMgl that it could be used for 
detecting dew points in the neighborhood of —75 C. 
This material was far more sensitive than required at 
ordinary temperatures and therefore no work was 
done with it. It should be noted, however, that it 
will give satisfactory tests with commercial oxygen 
at ambient temperatures at —45 C and so could be 
used under arctic conditions. A compound EtM- 
MgCl may be even more sensitive, but this was not 
investigated. 

A reagent made from benzophenone and iodoben- 
zene is less sensitive to water and is, therefore, suita¬ 
ble for testing gases with higher moisture content. 
The compounds which were investigated are listed in 
Table 1 together with a sensitivity, expressed in rela- 


Table 1. Reaction products of Grignard reagents and 
ketones which are sensitive to moisture. 


Grignard reagent 

Ketone 

Relative 

times Color change 

1. Ethyl magnesium 

Michler’s 

0.1 

Colorless to 

bromide(EtMMgBr) 


green 

2. Methyl magnesium 

Michler’s 

1.0 

Colorless to 

iodide (MeMMgl) 



light blue 

3. Methyl magnesium 

Benzo- 

25 

None at 25 

iodide 

phenone 


minutes 

4. Phenyl magnesium 

Michler’s 

5.0 

Yellow to dark 

iodide 



blue-green 

5. Phenyl magnesium 

Benzo- 

4.0 

Colorless to 

iodide 

phenone 


rust 


atmosphere of dry nitrogen. The Grignard reagent 
was added to an anhydrous solution of Michler’s 
ketone (tetramethyl-diaminobenzophenone) in ben¬ 
zene. 

Apparatus. A glass ampule was prepared from 
Y\-\n. tubing about 4 in. long. One end of the tube 
was drawn to a tip and sealed off. Retaining plugs 
of woven glass fiber were inserted with dry sand. 
After baking out, a measured portion of the reagent 
was introduced into the open end of the tube in an 
atmosphere of dry nitrogen, and this end of the tube 
was immediately drawn to a tip and sealed. Bench 
apparatus for introducing the reagent and the sealing 
of the ampule was designed which doubtless could 
be extended to large-scale production. 

The reagent remains sensitive after heating (in 
absolutely dry ampules) to 110C and cooling to 
—78 C, and after storing for six weeks at 65 C. 
However, long periods of storage (6 months or 
more) introduced changes in the calibration of the 
ampules and indicated discouraging supply problems 
in the field. This may be in part due to the extreme 
sensitivity of reagent to moisture and the slow evo¬ 
lution of moisture from the sand support, glass of 
the container, etc. Silica gel was found to be entirely 
unsuitable as a support in place of sand, because of 
the difficulty of moisture removal by ordinary baking 
procedures. 

The apparatus and the method of making mois¬ 
ture determinations is at once very compact and very 
simple. 




























322 


INSTRUMENTS FOR TESTING OXYGEN 


Suitable apparatus is shown in Figure 9. This 
consists of: (1) a coupling for attaching to the cyl¬ 
inder, (2) needle valve which will stand 3,000 psi 
with a fine adjustment to provide very low rates of 
flow from this pressure, (3) a holder for the glass 
ampule with provision for breaking the tips of the 
ampule after insertion and flushing with gas sample, 
(4) indicator for flow rate. 



Figure 9. General view of complete chemical test in¬ 
strument for moisture detection. 


All parts must be made of substances which do 
not adsorb water; metal is the only safe material. 
Even with metal, crevices and corners must be 
avoided because of the difficulty of purging moisture 
therefrom. 

Operation. The operation of the apparatus shown 
in Figure 9 is as follows. The apparatus is attached 
directly to a high-pressure cylinder of oxygen, the 
cylinder valve opened and the needle valve adjusted 
to give the approximate flow with a blank tube 
(which may be an ampule from a previous determina¬ 
tion) inserted in the ampule holders. A desirable 
flow is approximately 1 1 per min and is indicated by 
flow meters of the Rotameter type. The blank tube 
is then removed from the holder and a fresh ampule 
inserted. After allowing a short interval of time for 
flushing, the crusher mechanism at each end of the 


holder is actuated to break the tips of the ampule, 
the needle valve quickly adjusted for accurate flow 
and the time observed. Color formation will occur 
at the top of the tube and slowly extend downward 
during progress of the test. The time is recorded 
for the movement of the color front along a given 
distance and this is compared with data furnished 
for the conditions of temperature and flow for the 
batch of ampules. The boundary condition 0.02 mg 
per 1 moisture content was observed to give a move¬ 
ment of the color front of approximately 1 in. in 
2 l / 2 minutes at normal room temperature. 

Several difficulties were experienced with the 
operation of this instrument. 

1. The color boundary was not always sharp or 
uniform across the diameter of the tube. This was 
presumably due to channeling of the gas in the sand. 

2. A long purging was required when the appara¬ 
tus was first attached to a cylinder of oxygen. 

3. A variation of as much as threefold was obtained 
by different ampules in determinations upon a single 
cylinder of oxygen. 

Data shown in Table 2 are typical of the results ob¬ 
tained with this apparatus which represents a large 
number of ampules observed in the apparatus when 
connected to a single cylinder of oxygen which gave 
a reading of 0.018 mg per 1 at the start of the test 
and 0.024 mg per 1 at the end of the test by the 
electrical conductivity methods of the Bureau of 
Standards 22 (this variation is due to a reduction of 
the pressure in the cylinder from 1,400 psi to 600 psi 
during the investigation of the colorimetric moisture 
tester). 

In a further attempt to simplify the apparatus and 
overcome some of these difficulties, the ampule was 
reduced in size and increased in uniformity. The 
apparatus was modified by elimination of the needle 
valve and substitution of a pop-off connection and 
by-pass valve before the ampule connection for fine 
adjustment of the flow in the main cylinder valve. 
No material improvement in the functioning of the 
system resulted and it became increasingly evident 
that storage deterioration in the ampules was a seri¬ 
ous problem. 

Although the apparatus is extremely compact and 
the method of analysis is inherently simple, the degree 
of judgment required in making the reading is ex¬ 
traordinarily great and believed to be unsuited for 
use by unskilled personnel in the field. Although the 
apparatus is far less expensive than the Bureau of 
Standards apparatus in initial cost, the cost of ampule 








INSTRUMENTS FOR DETERMINING MOISTURE CONTENT OF GASES 


323 


Table 2. Test data on MeMMgl made upon a single 
cylinder. 


Moisture content 

Moisture content 

indicated at 

indicated at 

0 to 24 mark 

24 to 5 mark 


A* Flou> rate 1 l per min f 


0.36 mg per 1 

0.031 mg per 1 

0.024 

0.023 

0.021 

0.013 

0.024 

0.033 

0.026 

0.024 

0.036 

0.031 

0.024 

0.023 

0.021 

0.013 

0.024 

0.033 

0.026 

0.024 

0.023 

0.023 

0.051 

0.038 

0.031 

0.033 

0.021 

0.023 

0.019 

0.022 

B.% Flozv rate 0.400 l per 

min 

0.023 

0.023 

0.051 

0.038 

0.031 

0.033 

0.021 

0.023 

0.019 

0.022 

0.030 

0.036 

0.028 

0.039 

0.027 

0.016 

0.037 

0.021 

0.019 

0.017 

0.020 

0.016 

0.018 

0.016 

0.017 


0.020 


0.027 

0.022 

0.025 

0.020 

0.022 

0.027 

0.120 mg/1 § 

0.04 mg/1 

0.027§ 

0.23 

0.32§ 

0.25 

0.34 

0.34 


* The initial pressure of this cylinder is 1,400 psi and gave a 
reading of 0.018 mg per 1. At the end of observations the pressure 
was 600 psi and the electrical conductivity method gave a reading 
of 0.024 mg per 1. 

t December 29, 1943. 
t December 31, 1943. 

§ The flow was at normal temperature, 78 F. Values were obtained 
consecutively after connecting the instrument. The instrument was 
then disconnected, exposed to room air for a few minutes, reconnected 
and the fourth point measured. The initial pressure was 600 psi 
(same cylinder as reported in Table 1) and the final pressure 550 psi. 
Reading on the NBS instrument was 0.024 mg per 1 before and 
after tests B. 

supplies would be far in excess of the operating cost 
of the Bureau of Standards instrument. 

Suggested Further Development. The chemicals 
herein described are undoubtedly interesting as indi¬ 
cators for extremely low concentration of moisture. 


It is believed that in order to make the system useful 
as a means of determining moisture much work re¬ 
mains to he done upon the physical properties of the 
system. For example, the flow of the gas through the 
packed bed of sand needs to he more accurately con¬ 
trolled, inasmuch as this is a time-absorption phe¬ 
nomenon and not an equilibrium condition. Also, it 
will he necessary to control more accurately the sur¬ 
face of the supporting medium (sand) and the amount 
of reagent adsorbed thereon. Possibly, if these prob¬ 
lems are satisfactorily solved in a low-cost ampule 
the method will find extensive use in testing a number 
of dry gases. 

14 3.2 Frost Point Instrument for Deter¬ 
mining Moisture Content 
of Gases 

A moisture-measuring instrument of the frost- 
point (or dew-point) type gave promise of being 
very compact and simple to operate in the field, 
within the range of accuracy required for determin¬ 
ing the moisture in cylinder oxygen gas. The method 
is an improvement over the colorimetric method just 
described in that it is absolute, no calibration being 
necessary and no charts being needed in performing 
analyses. The moisture content is read directly from 
a gauge dial and the result is independent of varia¬ 
tions in ambient temperature, oxygen pressure, and 
other external variables. 

If determinations are made on an accept or reject 
basis of defined boundary value, for example, 0.02 
mg per 1. the manipulation of the test apparatus be¬ 
comes very simple and the time required per deter¬ 
mination is of the order of 1 min. 

Compressed carbon dioxide is used as refrigerating 
means (about 5 g per determination, or 1 lb per 100 
determinations). This together with small dry cells 
for the operation of the flashlight bulb constitute all 
of the supplies necessary for the operation of the 
apparatus. Four or five 1 of oxygen gas sample is 
adequate for a determination. 

Experimental apparatus was developed and built 3 
by Arthur D. Little, Inc., from which two production 
models were made; one by the Mine Safety Ap¬ 
pliances Company, and one by the Foxboro Instru¬ 
ment Company. Several instruments of each model 
were produced for examination and testing by the 
Services. 

Design Features and Description of Experimental 
Model. A frost point instrument for the proposed 






324 


INSTRUMENTS FOR TESTING OXYGEN 


use includes three fundamental elements: (1) means 
for cooling the target on which the dew or frost is 
to collect and for holding the temperature constant 
at any desired value, (2) means for measuring the 
temperature of the target, and (3) an optical system 
for readily observing small deposits of dew or frost. 

The experimental assembly of these elements is 
shown in Figure 10. The target, a small cylindrical 



Figure 10. Tester body of McMahon dew-point ap¬ 
paratus. 


copper plug, is shown at 5. This is enclosed in a 
chamber through which the gas sample is caused to 
pass. The target is cooled by impinging upon its 
lower surface a stream of carbon dioxide from a re¬ 
stricted orifice. The expansion takes place from full 
cylinder pressure for carbon dioxide to a lower 
pressure and hence, fixed temperature, controlled by 
a regulator to regulate the temperature of the target. 
The target is provided with a ring-shaped cavity 
connected by fine capillary tubing to a pressure gauge 


and charged with carbon dioxide to constitute a vapor 
pressure thermometer for measuring the temperature 
of the target. The target is directly illuminated from 
light passing through a transparent window 6 and 
deposits are observed through telescopic systems 1 
and 2. Not shown in Figure 10 are connection facili¬ 
ties for carbon dioxide and gas sample, light source 
for illuminating target and pressure regulator, and 
for adjusting expansion pressure of carbon dioxide 
at the target. Figure 11 shows the relative position 
of the component parts of the instrument within the 
case. 

Control of temperature is accomplished by allow¬ 
ing compressed carbon dioxide (from the gas phase 
above liquid) to expand through a small orifice. The 
stream of cold carbon dioxide, partially liquefied, is 
directed against the underside of a small copper block, 
the target 5. Because of the excellent heat transfer 
coefficient between the copper block and the stream 
liquid of carbon dioxide spray (approximately 5 g 
per min flow), the target is cooled to within a few 
degrees of the temperature of the spray within 20 to 
30 sec. By controlling the pressure of the expanded 
carbon dioxide, a temperature is fixed at any desired 
value as shown in Figure 12. Operation is best when 
the pressure after expansion is greater than 5 atm 
abs, the triple point for carbon dioxide, since solid 
carbon dioxide will not be present to clog the ap¬ 
paratus. The triple point appears to lie quite close 
to the boundary frost point for which the moisture 
content is 0.020 mg of water per 1 STP. Figure 12 
is the vapor-pressure curve for carbon dioxide. 

Figure 13 is the frost-point curve for ice in which 
the vapor pressure is expressed as mg per 1 for a 
total pressure of 1 atm. 

Figure 14 is obtained by combining Figures 12 and 
13. It correlates the pressure of carbon dioxide in 
the vapor pressure thermometer with the moisture 
content of a test sample at the time of frost forma¬ 
tion. 

The expansion pressure is controlled by a simple 
pressure regulator or safety valve with an adjustable 
spring controlled by a knob and screw mechanism. 

The temperature of the target is measured by 
means of a carbon dioxide vapor pressure ther¬ 
mometer. An angular-shaped cavity in the target is 
connected to a pressure gauge and is charged with 
pure carbon dioxide at room temperature at a pressure 
of about 160 psi. The assembly is then sealed off 
permanently. Care must be used in choosing a suit¬ 
able ratio of target cavity volume to total volume of 


































































INSTRUMENTS FOR DETERMINING MOISTURE CONTENT OF GASES 


325 


the thermometer system in order that the pressure 
gauge indicate correctly the vapor pressure of carbon 
dioxide in the target cavity. 

The target material should be of high thermal con¬ 
ductivity, for example, copper, in order that the 
vapor pressure thermometer will give accurately the 
temperature of the external condensing surface. All 
connections to the target such as the tubular support 
and thermometer capillary should be of material with 
low thermal conductivity, for example, monel or 
stainless steel. 

The surface of the target upon which frost is to be 
observed is polished and then plated with nickel or 
bright chromium in order to produce a flat mirror as 
nearly specular as possible. Small scratches or dust 
are confusing to the observer. 


The optical system can best be described as a 
dark field condenser. Parallel light from a flashlight 
bulb and parabolic reflector enters the sample cham¬ 
ber through an annular Lucite window 6. The light 
is reflected from a conical shoulder in the sample 
chamber to the target surface from an oblique angle. 
If the target surface is a perfect mirror, all the light 
is reflected specularly, and none of it enters the lens 
tube located directly over the target. The whole in¬ 
terior of the sample chamber is blackened to prevent 
light from entering the lens tube by multiple reflec¬ 
tions. Specks of dew or frost condensing on the tar¬ 
get cause light to be scattered off at all angles, so that 
some of this light may enter the lens tube. To the 
observer, these specks appear as bright pin points 
of light in contrast to the relatively dark field. 



Figure 11. Assembly outline of McMahon dew-point apparatus. 































326 


INSTRUMENTS FOR TESTING OXYGEN 


The experimental model, with casing removed, is 
shown in Figure 15. In order to protect the small 
expansion orifice, a glass-wool filter is introduced 
to remove some matter from the carbon dioxide 
stream. 

Production Models. The external appearance of 
the Foxboro model is shown in Figure 16. A small 
flow-meter has been included to adjust the flow of 
sample gas. 

The Mine Safety Appliance model is shown in 
Figure 17. This instrument has been modified to 
include means for pressurizing the sample chamber 
in order to extend measurements to low moisture 
contents. For example, a sample of moisture content 
of 0.010 mg per 1 when pressurized to 2 atm abs 
will read 0.020 mg per 1 on the dial. In addition to 
a dry cell, a transformer has been included for opera¬ 
tion of the illuminating light from a 60-cycle power 
line. A well at the back of the case contains a supply 
of tools, connection tubing, and adaptors fitting vari¬ 
ous types of carbon dioxide and oxygen cylinders. 

If these instruments are to be used for the deter¬ 
mination of moisture in carbon dioxide, a single con¬ 
nection to the carbon dioxide cylinder may be made 



Figure 12. Relation of vapor pressure of C0 2 to tem¬ 
perature. 




Figure 14. Relation of moisture content to vapor pres¬ 
sure of COa. 









INSTRUMENTS FOR DETERMINING MOISTURE CONTENT OF GASES 


327 


through a forked line, one side of which connects to 
the sample chamber and the other side to the refrig¬ 
erating apparatus. 

Operation of Instrument. Connections from car¬ 
bon dioxide and oxygen cylinders are made through 
capillary copper tubing. It is desirable to purge the 
sample chamber well before releasing carbon dioxide 
to the refrigeration apparatus. Precautions for avoid¬ 
ing moisture in connections are to be observed. The 
initial deposit of frost near the frost point is ex¬ 
tremely light and requires careful observation. If the 
frost point is to be determined accurately the meas¬ 
urement may be made as a series of approximations 
“closing in” on the actual value. The instrument is 
most readily used for the acceptance or rejection of 
gas samples at some one moisture value for which the 
apparatus is adjusted and observance made for the 
absence or presence of deposits upon the target. 

Various forms of the apparatus described above, 
with careful manipulation, have given results accu¬ 
rately to ± 0.003 mg per 1 when the mirror surface 
of the target is excellent. Even with a poor mirror 
surface and clumsy manipulation an accuracy of 
± 0.01 mg per 1 is possible. A common source of 
error is the presence of a number of condensable 
gases or other impurity in the vapor pressure ther¬ 
mometer. 



Suggested Modifications and Further Research. 
The target and optical system of experimental models 
have not been perfected; improvement will lead to 
much greater accuracy and ease of determinations. 
Modifications and adaptation of other frost-point 



Figure 16. Foxboro type apparatus for determining 
moisture in aviator’s oxygen. 





Figure 17. Mine Safety type water vapor indicator. 




































328 


INSTRUMENTS FOR TESTING OXYGEN 


ranges may be made by substituting other condens¬ 
able gases in tbe vapor pressure thermometer and 
adjusting the carbon dioxide regulator. 

14 4 INSTRUMENT FOR DETERMIN¬ 
ING A COMBINATION OF 
PROPERTIES OF COMPRESSED 
OXYGEN GAS 

A cabinet-style water-vapor indicator of tbe elec¬ 
trical conductivity type, 22 manufactured by the 
American Instrument Company, was altered by re¬ 
arrangement of valves and connecting tubing to per¬ 
mit installation of a Model P Pauling oxygen 
meter 4 within tbe cabinet and upon the instrument 
panel of the water-vapor indicator. 6 A sensitive pres¬ 
sure regulator was installed between the oxygen sam¬ 
ple line of the water-vapor indicator and the Pauling 
oxygen meter to prevent damage to the latter. In 
addition, an exhaust of tbe oxygen sample line is 
provided with a connection for carbon monoxide test 
ampules developed by tbe National Bureau of 
Standards. 

It is, therefore, possible, with a single connection 
to an oxygen cylinder, to determine the cylinder 
pressure and moisture content (water vapor indi¬ 
cator), the partial pressure or percentage of oxygen 
(Pauling oxygen meter) and the concentration of 
carbon monoxide and certain other impurities, by tbe 
insertion of suitable ampules in tbe sample exhaust 
connection. 

14 5 COMBINED VAPOR-PRESSURE 
AND GAS THERMOMETER 

In connection with the operation of the oxygen 
generating units described in earlier chapters, it was 
believed desirable to develop simple, rugged ther¬ 
mometers which would be sensitive to 1 F over the 
entire working range, or roughly from —320 F to 
—150 F. A combined vapor-pressure and gas ther¬ 
mometer filled with oxygen or nitrogen seemed ideal 
for this purpose. 

The thermometer 10 ’ 11 ’ 12 comprises a Bourdon-type 
pressure gauge, a bulb, and flexible, armored capil- 

c The structural changes in the instruments were very 
kindly made by the National Bureau of Standards under the 
supervision of Dr. E. R. Weaver. Dr. Weaver and his 
associates also contributed many valuable suggestions to the 
construction and operation of this and other water-vapor in¬ 
dicators which they tested. 


lary tubing connecting tbe gauge and bulb. In order 
to insure accuracy as a gas thermometer, the gas 
volume of the Bourdon tube and tbe capillary tubing 
should be small relative to tbe volume of the bulb. 
Specifications are: 

1. Bulb. j4-in. OD. 0.035-in. wall, copper tubing 
10 in. long, welded shut at one end and fitted at tbe 
other end with a plug drilled to fit the connecting 
capillary tubing. 

2. Connecting tubing. Twelve ft of copper capil¬ 
lary with a volume of 0.064 ml per ft. It is covered 
with a flexible stainless steel protecting armor. 

3. Gauge. The gauge has the usual Bourdon tube 
and gear arrangement; Bourdon tubes of small vol¬ 
ume are to be preferred. Tbe dial of tbe gauge was 
graduated in degrees Fahrenheit as determined by 
calibration against a thermocouple and certain fixed 
points such as the boiling point of oxygen, ice point, 
etc. A sample calibration curve is given in Figure 18. 

4. Tbe thermometer is filled with pure oxygen or 
pure nitrogen to a predetermined pressure while the 
temperature of the bulb is held at a predetermined 
value. 



Figure 18. Scale divisions vs temperature for oxygen 
and nitrogen thermometers. 

The Tagliabue Manufacturing Company of Brook¬ 
lyn, New York, has worked out production methods 
for this thermometer which avoid the necessity for 
individual calibration. 10 


14 6 A DIAL-TYPE LIQUID 

LEVEL GAUGE 

Tbe standard manometer type of liquid level gauge 
in common use on stationary liquid oxygen plants to 
indicate the height of liquid at the bottom of tbe 
fractionating column, is not suitable for use on por- 





A DIAL-TYPE LIQUID LEVEL GAUGE 


329 


table generators because of its fragility and danger 
of spilling. The following differential pressure gauge 
was, therefore, developed for use on portable liquid 
oxygen generators. 16 

A sensitive double diaphragm similar to that em¬ 
ployed in the anneroid barometer, and a rack and 
pinion mechanism for translating the motion of the 
diaphragm into the rotation of a pointer spindle were 


enclosed in a gas-tight case provided with a pressure 
resistant dial glass. The case is provided with a lead 
for attachment to the lesser of the two pressures 
whose difference it is desired to measure. The con¬ 
nection to the interior of the diaphragm was used for 
the greater of the two pressures. The case of the 
meter was built to withstand the operating pressure 
of the rectification column. 



Chapter 15 

SUBMARINE PROBLEMS 

By S. S. Prentiss a 


INTRODUCTION 

he fact that there were certain undesirable 
limits of speed and cruising radius placed on 
submarines dependent on storage batteries for sub¬ 
merged propulsion prompted a study of operation of 
diesel and other combustion engines with combustion¬ 
supporting secondary fuels. NDRC undertook a 
threefold program which included (1) the genera¬ 
tion of large amounts of oxygen aboard submarines 
while surfaced, for use as secondary fuel while sub¬ 
merged, see Chapters 3 and 4, (2) the operation of 
diesel engines under submerged conditions, and (3) 
the disposal of exhaust gases from submerged sub¬ 
marines to minimize the chances of enemy detection. 
Auxiliary problems which later developed included 
the supply of oxygen and the removal of carbon 
dioxide from the atmosphere within submarines to 
permit long periods of submersion. 

15 2 OPERATION OF DIESEL ENGINES 
WHILE SUBMERGED 
(RECYCLED EXHAUST GASES) 

As a first approach to the propulsion of submerged 
submarines, it was proposed to use the diesel engines 
normally used for surface propulsion. A program 
was therefore undertaken to demonstrate the feasi¬ 
bility of operating diesel engines under conditions 
approximating those of a submerged submarine and 
to develop the optimum conditions for such operation. 
Such a program was carried out on small experi¬ 
mental diesel engines with satisfactory results. 

15.2.i Problems of Recycle Operation 

In order to prevent overloading and overheating 
of the diesel engine when operating on oxygen it is 
necessary to recycle exhaust gases as a diluent for 
the working fluid. (See Figure 1.) Since this ex¬ 
haust gas (water vapor and carbon dioxide) has a 
higher heat capacity than nitrogen, which is the oxy¬ 
gen diluent for air, the theoretical efficiency of an 
engine operating on recycle cannot be greater than 
87% of that obtained with air for the same com- 

a Technical Aide, Division 11, NDRC. 


pression ratio. In addition, ignition delay is ap¬ 
preciably greater than on air. 

Disposal of fixed gases presents a major problem 
in the underwater operation of diesel engines using 
“oxygen-recycle.” For this reason and for economy 
of secondary fuel, it is desirable to reduce the oxygen 
in the waste exhaust gases to as small a quantity as 
possible. The problem of oxygen disposal in the ex¬ 
haust from the two-cycle engine, which requires 
excess working fluid for scavenging, appeared to he 
more acute than with the four-cycle engine. In addi¬ 
tion to the above, engine noise (knocking) under most 
conditions of operation was greater than on air. 

15 2 2 Apparatus and Materials 

The tests were made, employing two different 
single-cylinder diesel engines and one 6-cylinder 
automotive type diesel, as described in Table 1. 


Table 1 



General Motors 
Model 1-71 

Waukesha 

CFR 

Hercules 

Model DJXB 

Power 

15 hp @ 1200 rpm 


77 lip @ 2600 rpm 

Type 

2 cycle with built- 
in blower-direct 
injection 

4 cycle with 

comet-type 

antechamber 

4 cycle, with Her¬ 
cules turbulence 
combustion chamb¬ 
er (automotive 
type) 

Size 

44 x 5, single 
cylinder 

31x41, 
single cyl¬ 
inder 

34 x 44, 6 cyl¬ 
inder 

Com¬ 

pres¬ 

sion 

ratio 

16 to 1 

15.5 to 1 

16 to 1 

Injec- 

GM standard unit 

Bosch fuel 

Bosch fuel pump 

tion 

equip 

ment 

injector 

pump and 
injector 

and injectors 


The engine was directly connected to a cradle-type 
electric dynamometer for measuring power. Tem¬ 
peratures, pressures, flow rates, gas composition, et 
cetera, were determined with regular laboratory in¬ 
struments and standard test procedures. Ignition 
delay was obtained with a Sunbury cathode-ray 
type engine indicator. 



330 







OPERATION OF DIESEL ENGINES WHILE SUBMERGED 


331 


All tests were made with commercial diesel fuel 
having the following specifications. 


Gravity, API 

37.0 

Cetane No., ASTM 

51 

Viscosity @ 100 F, SSU 

35 

Mid-boiling point, F 

504 

Final boiling point, F 

640 


15 2 3 Experimental Procedure 

The test procedure used conformed to the regular 
accepted standards covering the type of operation 
involved. In Table 2 are presented the principal 
operating conditions used for recycle operation. 


Table 2 



General Motors 
Model 1-71 

Waukesha Hercules 
CFR Model DJXB 

Speed, rpm 

900 and 1200 

950 

1200 

Load 

2 tO full 

Various 

i to full 

Temperature F, 
working fluid 
to engine 

250 

250 

250 

Temperature F, 
oil 

180 

150 

170 

Temperature F, 
water out 

180 

212 

170 

Back pressure, in. 
of Hg 

0.5 (normally) 

0.1 (normally) 

0.5 

Fuel injection 
angle-degree 

14 BTDC 


14 BTDC 


15 2 4 Results and Conclusions 

No special problems were encountered in operating 
the test engines on oxygen recycle within the range 
of one-half to full rated power. All the test work 
proceeded without incident. It was found, however, 
that to avoid the possibility of an explosion it was 
advisable to keep the oxygen concentration at the 
engine intake below 50%. 

Under regular recycle operation for the various 
test engines, oxygen loss varied from 10 to 17% at 
full load to 25 to 35% at approximately one-half 
load (see Figure 2). In attempts to reduce this loss 
the waste exhaust gas from the larger GM engine 
was fed to the smaller CFR engine (see Figure 3). 
In this type of series operation the overall oxygen loss 
was reduced to 4%. In further tests, water scrub¬ 
bing of the exhaust gas was employed and by this 
method oxygen losses were reduced to 2% (see 
Figure 4). Using this system and feeding oxygen 
containing 5% argon increased engine efficiencies 
over those obtained with 100% oxygen feed and re¬ 
duced the noise level to at least that obtained with 
air (see Figure 5). However, the water and power 
requirements necessary for this type of operation may 
be prohibitive. 

It was concluded from these tests that oxygen 
recycle operation of diesel engines is feasible and 
that sufficient data are available 2 to be able to set 



TO 

WASTE 


Figure 1. Schematic diagram of test setup of 1 cylinder 2 cycle GM diesel engine. 

















































332 


SUBMARINE PROBLEMS 



Inoicatco H P 


Figure 2. Oxygen recycle tests of 1 cylinder GM and 
CFR diesels. Per cent CL lost at various loads. 

down and compare the various methods of operation 
from the standpoint of equipment and power require¬ 
ments to enable an approximation of the optimum 
method of operation. The whole program, however, 
was abruptly terminated when the Navy decided that 
the operation of submarines by diesel engines was not 
permissible because of the high noise level. 


15 3 DISPOSAL OF ENGINE EXHAUST 
WHILE SUBMERGED 

15 3 1 Jet Dispersion into Sea 

An important auxiliary problem to the operation of 
diesel engines aboard submerged submarines was the 
disposal of exhaust gas therefrom in such a manner 
as not to add to the visibility of the submarine from 
air reconnaissance. The problem was never clearly 
defined as the definite restriction of visibility to over¬ 
head observation ; it was interpreted, therefore, as one 
of dispersing the gas into the sea in the form of bub¬ 
bles sufficiently small as to be completely absorbed 
while rising toward the surface, from a minimum or 
critical depth of 30 ft. The possibilities of the gas 
cloud dispersal method are illustrated in Figure 6. 

The plan proposed for full-scale operation involved 
internal combustion engines to produce about 2,700 
indicated horsepower and 188 lb moles per hr of hot 
raw exhaust gas consisting of 86.7 lb moles per hr 
of water vapor (1,560 lb of steam), 86.7 lb moles 
per hr of carbon dioxide (3,800 lb), and 15.3 lb 
moles per hr of oxygen and argon. On the dry basis, 
the dehumidified exhaust gas would then contain 85% 
carbon dioxide by volume and 15% oxygen and 
argon. A study of gas cloud solution in sea water 


ios ft 3 / m\n 


Fuel -7.35 lbs/hr 



% 

COx 

37.2 

Ox 

22.3 

CO 

0.1 

Ni 

0.9 

HxO 

39.5 


Oxygen 

6.06 FrVMw 
29 .S 8 L»»/H« 

.<LP 


Oxygen 

0.95 FtVM«m 
4.fc4 L*s/H« 


9 6 




COx 

Ox 

CO 

Nj. 

HxO 


-2k 

60.3 

24.4 
0.2 
1.3 

13.8 


Fuel-2.ISlbs/hr 


In 


Out 


G./A. Diesel. 


105 Ft 

6.1 FtV/A.n 

0.1 La/A... 

4.2 FtV>\,n 


10.8 FtV/4 1n 


-% 



°/o 


% 

COx 

39.5 


COx 

57.9 

COi 

7S.6 

02. 

17.3 


Ox 

25.3 

Ox 

7.4 

CO 

0.1 


CO 

0.2 

CO 

0.2 

Ni 

l .1 


Nx 

1.5 

Nl 

1.4 

HxO 

42.0 


HtO 

1 5.0 

HxO 

15.4 


O 2 . Fccp —14.7 


* 


13.92 BHP 
22.02 IHP 

0.335 Lbs Fucl/IHP-HR 
1.34 Lb« Ox/lHP-HR 


Overall Performance 

16.56 BHP 
26.64 IHP 

0.359 Lea Foeu/IHP-HR 
1.28 LbsOx/iHP-HR 
4 . 1 % OVERALL Ox LOSS 


< .► 
?**- 
o’ 0 - 
t- «> 


Overall Oi Loss 
%Feed-4.I 


2.64 BHP 
4.62 IHP 

0.474 LbsFuci./|HP - HR 
I.Ol Lbs Ox/lHP-HR. 


Figure 3. Series operation of 2 cycle GM and 4 cycle CFR diesels. Oxygen recycle operation. 






































































































DISPOSAL OF ENGINE EXHAUST WHILE SUBMERGED 


333 


was made with bubbles of various controlled sizes. 
The bubble of critical or maximum diameter that will 
dissolve from a given depth with exhaust gases of 
different composition are shown in Figure 7. 

A series of tests was made on a small scale in a 
vertical glass column and later repeated in Boston 
harbor (see Figure 8 and Figure 9). For dispersing 
the gas, injectors were found to be more economical 
of power than porous plates. A two-stage water in¬ 
jector is more economical than a single stage, as 
shown in Figure 10. For a constant total outlet and 
arrangement of the holes in the final disperser, a 
large number of holes is economical on total power 
and water; however, nozzles of diameters less than 
0.3 in. are not recommended because of the possibil¬ 
ity of clogging. Details of experimental nozzles are 
shown in Figures 11 and 12. 

The experimental results may be summarized in 
the following application to a submarine diesel engine 
developing 2,700 hp. 1 When operating 110 of the 
recommended dispersers in parallel to share the full- 
scale gas rate, at a depth of 30 ft, the necessary water 
pump would handle 1,500 gal per min and develop a 
pressure difference of 62 psi, consuming 54 theoreti¬ 
cal hp. If the total dry gas from the dehumidifier 
(657 cu ft per min at 1 atm abs and 70 F) is com¬ 


pressed isothermally from atmospheric pressure to 
the pressure at the inlet to the dispersers (58 psi 
gauge) 67 theoretical hp are required. The total 
power for both gas and water is then 121 theoretical 
hp, or 155 shaft hp with 83% efficiency for the water 
pump and 75% efficiency for the gas compressor. 
The total shaft hp required is then 5.8% of the 2,700 
indicated hp developed by the internal combustion 
engines producing the gas which contains 3.800 lb/hr 
of carbon dioxide and enough oxygen and argon to 
give a mixture containing 85% carbon dioxide by 
volume. The velocity of the water, through the noz¬ 
zle in the injector, would be approximately 26 miles 
per hr and the velocity of the mixture of water and 
gas (assuming water and gas volumes are additive at 
the outlet of the disperser at 30 ft depth) would be 
74 mph. 

15 3 2 Sea Water Scrubbing 

A superficial investigation was made of apparatus 
for scrubbing exhaust gases with sea water inside of 
the pressure hull. The prohibitive size of the equip¬ 
ment for completely dissolving the exhaust gases in 
sea water within the pressure hull caused this method 
to be discarded in favor of the method of dispersing 
exhaust gases into the sea. 



Figure 4. Oxygen recycle operation of 1 cylinder CFR diesel engine with argon using exhaust gas scrubbing. 
























































FUEL ECONOMY LBS/I HP-HR OXYGEN ECONOMY LBS/I HP- HR IGNITION DELAY-DEGREES Oj LOSS % FEED 


334 


SUBMARINE PROBLEMS 


^ 100 %0 2 WITH SCRUBBING 
© 95 % 0 2 + 5 % A WITH SCRUBBING 



1.4 1.6 1.8 2.0 2.2 2.4 

FUEL RATE - LBS /HR 

Figure 5. CFR diesel-recycle operation. Performance curves using 100% 0 2 and 95% O s + 5% A with FLO scrubbing, 
and 100% 0 2 without scrubbing. 














DEPTH-FT DEPTH - FT 


AIR CONDITIONING 


335 



Figure 6. Exhaust gas cloud dispersal at various depths. 



0 .1 .2 .3 .4 .5 .6 .7 .8 .9 1.0 l.l 1.2 1.3 


CRITICAL DIAMETER-MM 

Figure 7. Effect of depth on critical diameter of gas 
bubbles in (1) natural and (2) artificial sea water. 


15 3 3 Recommendations for Future 

Research 

The operation of other forms of internal combus¬ 
tion power mechanisms (for example, gas turbines) 
on recycled gases should be studied. The substitution 
of other power source in the submarine may eliminate 
objections to noise, et cetera. Means for entirely 
eliminating exhaust gases within the hull should be 
developed along the lines set forth under “Air Con¬ 
ditioning.” This may be practical for low-power 
(50 to 100 hp) and thus reduce the hazards of de¬ 
tection when the submarine is “lying low.” 

15 4 AIR CONDITIONING 

The long periods of submergence indicated by the 
foregoing form of propulsion made it desirable to 
provide means for maintaining breathing standards 
in the submarine atmosphere for long periods of 
time, preferably indefinitely. Table 3 presents a com¬ 
parison of methods for maintaining normal atmos¬ 
pheric conditions on a submarine. 













336 


SUBMARINE PROBLEMS 


Table 3.* Comparison of estimated volumes and weights of present and proposed chemical and mechanical methods for 
maintaining normal atmospheric conditions on a submarine; (calculations based on 60-man submarine crew) (volumes in 
cu ft and weights in lb). 






Keyes unit 

Stored liquid 


Present 


Chlorate 

and C0 2 

0 2 and C0 2 


method 

KOXor MOX 

candles 

sea water 

sea water 

Basis for 

(LiOH & 0 2 ) 

canisters 

and LiOH 

scrubbing 

scrubbing 

calculations 

Volume Weight 

Volume Weight 

Volume Weight 

Volume Weight V 

r olume Weight 


75 hr C0 2 absorbing 
18 hr 0 2 available 


Canisters 

15.0 

525 

45.0 

2,421 

15.0 

525 

t0.15 

18 



Candles 





2.7 

279 

23.0 




Cylinders 

14.0 

700 









Mechanical 







23.0 

X 

23.0 

X 

apparatus 



t 


3.0 

84 

17.0 

X 

5.0 

X 

Total 

29.0 

1,225 

45.0 

2,421 

20.7 

888 

40.15 

X 

28.0 

X 

75 hr CO 2 absorbing 











75 hr 0 2 available 











Canisters 

15.0 

525 

45.0 

2,421 

15.0 

525 

t0.6 

75 



Candles 





11.3 

1,170 





Cylinders 

64.4 

3,220 









Mechanical 







23.0 

X 

23.0 

X 

apparatus 



t 


3.0 

84 

17.0 

X 

20.0 

X 

Total 

79.4 

3,745 

45.0 

2,421 

29.3 

1,779 

40.6 

X 

43.0 

X 

300 hr CO 2 absorbing 











300 hr O 2 available 











Canisters 

60.0 

2,100 

180.0 

9,684 

60.0 

2,100 

12.4 

300 



Candles 





44.7 

4,680 





Cylinders 

252.0 

12,600 









Mechanical 







23.0 

X 

23.0 

X 

apparatus 



t 


3.0 

84 

17.0 

X 

75.0 

X 

Total 

312.0 

14,700 

180.0 

9,684 

107.7 

6,864 

42.4 

X 

98.0 

X 


X Data lacking. 

* Ref: Research Memorandum No. 2-44 NAVSHIPS (330), March 21, 1944. 
t Assumes use of portable blowers now on submarines, 
t Not canisters but KOH containers. 




Figure 8. Navy Yard runs. Dispersion of 85% CCh— 15% 0 2 in 30 feet of salt water. Disperser: Type R with Rich¬ 
ards Pump. Observations in bright sunlight. 










NUMBER OF UNITS FOR FULL SCALE PULL SCALE WATER RATE- 6PM 


AIR CONDITIONING 


337 




Figure 9. Requirements for complete absorption of 85% 
CO*—15% O, mixture in 30 feet of sea water. 


15 4 1 Supply of Oxygen 

Of the methods of supplying oxygen for breathing 
purposes on a submarine, NDRC contributed only 
the development of a generator for separating atmos¬ 
pheric oxygen. This is a compact unit operating with 
one torpedo-charging air compressor and producing 
approximately 20 lb of liquid oxygen per hr while 
the submarine is surfaced. This liquid oxygen can 
then be slowly evaporated while the submarine is 
submerged and thus replenish the oxygen supply. 

15 4 2 Removal of Carbon Dioxide 

The results of a survey of methods of absorbing 
carbon dioxide are summarized in Table 4. 3 Two of 
these methods were selected for experimental evalua¬ 
tion. and full sized units were built for demonstration 
purposes. 

The first of the methods developed was scrubbing 
with sea water as shown in the flow sheet, Figure 
13. s ’ 4 - 3 ’ 6 The unit operated with an absorption tower 
5 ft high, packed with 1-in. Raschig rings. The ab¬ 
sorption tower was operated at a relatively high 
pressure, that is, the ambient pressure of the sea, 
which varies with the depth of submergence. The 
air was compressed to the operating pressure of the 
tower, scrubbed with sea water, and then expanded 
into the hull of the submarine. Inasmuch as some 
cooling takes place, the operation of the unit may lead 



Figure 10. Critical tank data—0.85 mm bubble. Cal¬ 
culated for full scale operation comparing one and two 
stage dispersers. 








338 


SUBMARINE PROBLEMS 



WATER 

INLET 


I'/a"PIPE MI ^ URE 
THREAD 0UTLET 



STANDARD I '/ 2 " BRASS 
PIPE CAP 


•V D 


Figure 11. Hancock ejector with water nozzle. 


to a reduction in the operation of other air condition¬ 
ing systems on the submarine. In another form of the 
apparatus, a jet-absorption unit is substituted for the 
packed tower, with a consequent reduction in the size 
of the equipment (see Figure 14). 


GAS 

INLET 

t STANDARD Ve" 



Figure 12. Brass Richards pump used in series with 
Sprayco nozzle in two-stage dispersal. 


A second form of apparatus 3 ’ 4 ’ 5 - 6 employs ethanol- 
amine as the scrubbing agent as shown in Figure 
15. This system has the advantage that it may be 
completely contained in the hull of a submarine and 
therefore may be operated at the pressure of the sub¬ 
marine atmosphere. A suitable proportion of the 
atmosphere of the submarine may he circulated 
through the ethanolamine absorption tower and re¬ 
turned to the submarine atmosphere. The carbon 
dioxide is then desorbed from the ethanolamine and 
pumped overboard into the sea or compressed into 
pressure vessels. 

15 4 3 Recommendations for Future 
Research 

The apparatus developed so far is a first attempt. 
There should be opportunity for reducing the size and 
power requirements of this equipment by investiga¬ 
tion and development of absorption equipment. 







































































































AIR CONDITIONING 


339 


Tabi.e 4. Summary of pertinent facts about processes for carbon dioxide removal from air in submarines. 


Estimated 




Process 

volume 
cu ft 

Estimated 
power hp 

Process oxygen 
required, lb per hr 

Remarks 

la. Refrigeration 
with liquid 0 2 

Not estimated 

Negligible 

28 

In addition to high oxygen there is uncer¬ 
tainty about C0 2 deposition which will neces¬ 
sitate considerable development. 

lb. Refrigeration 

Not estimated 

3 

15 

Same as for la. 

with liquid 0 2 
and Freon 

lc. Same as (lb) plus 
recovery of latent 
heat of condensation 
of C0 2 

Up to 165 

7-15 

5 

The uncertainty regarding the C0 2 deposition 
will mean considerable development. Most of 
the volume is that of the vacuum pump; this 
might be reduced by changes in process. 

Id. Refrigeration 
by expander 

Not estimated 

18 

0 

In addition to high-power requirement process 
will require considerable development. 

2a. Adsorption, 
low pressure, 

0 2 refrigeration 

Not estimated 

Negligible 

28 

In addition to the high 0 2 requirement this 
process would require considerable develop¬ 
ment. 

2b. Same as (2a) 
but with Freon 
refrigeration 

195 

7 

0 

Requires considerable development. Hopeful, 
however, because C0 2 deposition less uncer¬ 
tain than in process 1. Most of the volume 
is that of the vacuum pump; this might be 
reduced by changes in process. 

2c. Intermediate 
pressure; expander 

Not estimated 

18 

0 

In addition to higher power, would require 
considerable development. 

refrigeration 

2d. High pressure 
adsorption 

30 

17 

0 

Assumes compressor already available. Un¬ 
tried and would need considerable develop¬ 
ment. 

3a. Sea water scrub¬ 
bing—1 atm 

75 

10-50 

0 

Power varies with depth. Power is chiefly to 
pump water out. A simple process requiring 
little development. 

3b. Sea water scrub¬ 
bing—50 lbs per sq in. 

31 

6-11 

1.2 

(2/1 lb NO 

Power varies with depth. A simple process 
requiring little development. 

3c. Sea water scrub¬ 
bing at sea pressure 

32 

4-10 

0.8-1.0 
(1.4/1.8 lb NO 

Power varies with depth. Power chiefly for 
air compression. A simple process requiring 
little development. 

4. Scrubbing with 
Amine 

14 

0.5 for 
mechanical 
power. 9.5 
for heat 

0 

Similar processes in use so little development 
required. 

5a. Absorption by 

LiOH 

62 

Negligible 

0 

This is good for only 320 hours. Volume is 
that for storage of chemical. 

5b. Absorption by 

k 2 o. 

180 

Negligible 

0 

This supplies necessary oxygen. Remarks 
under (5a) also apply. Chemical is hazardous. 








340 


SUBMARINE PROBLEMS 


TYPICAL CONDITIONS AT SUBMERGEO 
OEPTH OF 170 FEET 


_ r -_AQJUSTING AIR AT 

SEA PRESSURE 


PRESSURE 

CONTROLLER 


AIR-ACTUATED 
CONTROL VALVE 



WATER 


C0 2 REMOVED AT RATE 
OF 6 LB PER HR 


Figure 13. Sea water pilot plant demonstration unit. 



































































AIR CONDITIONING 


341 


SEA LEVEL 



Figure 14. Schematic diagram of jet-type air scrubber unit installed in submarine. 































































342 


SUBMARINE PROBLEMS 


C0 2 COMPRESSOR 



Figure 15. Process flow sheet of S-2 unit. C0 2 removal by ethanolamine scrubbing. 












































APPENDIX A 

DATA ON AIR AND ITS COMPONENTS 


Data 

Nitrogen 

Enthalpy (for temperatures below 0° F). 

Enthalpy. 

Vapor pressure. 

Density of gaseous nitrogen, lb/cu ft .. 

Temperature entropy diagram. 

Temperature entropy diagram. 

Temperature entropy diagram. 

Thermal conductivity. 

Viscosity. 

Argon 

Enthalpy. 

Vapor pressure. 

Density . 

Thermal conductivity. 

Viscosity. 

Oxygen 

Enthalpy. 

Vapor pressure. 

Density . 

Temperature entropy diagram. 

Temperature entropy diagram. 

Thermal conductivity. 

Viscosity. 

Helium 

Enthalpy. 

Temperature entropy diagram. 

Carbon Dioxide 

Enthalpy. 

Vapor pressure. 

Density . 

Temperature entropy diagram .. 

Thermal conductivity. 

Viscosity. 

Air 

Enthalpy ... 

Enthalpy of oxygen-nitrogen mixtures at 14.7 psia 
Enthalpy of oxygen-nitrogen mixtures at 75 psia . 
Enthalpy of oxygen-nitrogen mixtures at 150 psia . 

Enthalpy entropy diagram of air.• • • 

Vapor pressure of liquid oxygen and nitrogen mixtures . 
Dew-point pressures of gaseous oxygen-nitrogen mixtures 

Equilibrium of oxygen-nitrogen mixtures. 

Equilibrium of nitrogen-argon mixtures. 

Equilibrium of oxygen-argon mixtures. 

Liquid-vapor equilibrium for oxygen-nitrogen system . . 

Density of air. 

Temperature entropy diagram for air. 

Temperature entropy diagram of air. 

Thermal conductivity of air. 

Viscosity of air. 

Viscosity of liquid nitrogen-oxygen mixtures . . . . 


Curve Number 


G-602.301 

G-602.31 

G-602.51 

G-602.60 

G-602.65 

G-602.66 

G-602.67 

G-602.80 

G-602.90 


G-603.30 

G-603.50 

G-603.60 

G-603.80 

G-603.90 

G-605.30 

G-605.50 

G-605.60 

G-605.65 

G-605.66 

G-605.80 

G-605.90 

G-6l»y. 30 
G-609.65 


G-675.30 

G-675.51 

G-675.60 

G-675.65 

G-675.80 

G-675.90 


G-815.30 

G-815.31 

G-815.32 

G-815.33 

G-815.34 

G-815.50 

G-815.51 

G-815.52 

G-815.53 

G-815.54 

G-815.56 

G-815.60 

G-815.65 

G-815.66 

G-815.80 

G-815.90 

G-815.91 


343 






















































ENTHALPY 

OF 

NITROGEN 


-5a 


120 


BASE- 

H *0 FOR VAPOR AT-460*F ANO 0 PRESSURE 


240° 


-60* 


344 


G-602.301 






























































































































































































































































































































































































































































































3000— 


BASE 

IDEAL GAS AT -459.69 


NOTE 

FOR TEMPERATURES BETWEEN 
300* F AND 700* F, SEE PAGE 2 


ENTHALPY 

(TOTAL HEAT) 

OF 

NITROGEN 



G-602.31—Part 1 


345 




































































































































































































































































































































































































































































346 


G-602.31—Part 2 
















































































































































































































































































































-330 -320 -30 -300 -290 -280 -270 - 260 -250 '240 -230 



G-602.51 


347 


-330 -320 -310 -300 -290 -280 - 270 - 260 -250 - 240 - 230 












































































































































































































































































DENSITY 

OF 

NITROGEN 



348 


G-602.60 




















































































































































































































































































































































































































































G-602.65 


349 


340 -320 -300 -280 -260 -240 -220 -200 -180 -160 -140 420 -100 -80 -60 -40 -20 0 *20 *40 *60 *80 *100 *120 *140 *160 *180 *200 *220 *240 























































































































































































































































































































































































































































2 as 


>o>obi § § I £ 8 


TEMPERATURE - ENTROPY 
DIAGRAM 
FOR 

NITROGEN 


a OOOQQO o O 

cn ® r>- (2 ifi 't ro cm 


jul 

P 

1 

w 

xpx 


I 

w 

w> 

FH 



V 

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PRESSURE .LBS./SO.IN. ABS. 

Y p \ 

3 

3 


A 

A 

yx 

p 

p 

A 

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xA 


LI 

\ 


i| 

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iSr 


\ \ \ 


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S 


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§ 

PRESSURE,LBS./SQ IN ABS.) 

.V rv 'v: iv -t . v u v—i 

XA 

s 

\ 

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s 

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A 

§ 

Yn 


S 



O O O O 

88 8 § § 

® r- ® m t 


88 


ro 


o> co to »n ro 


350 


G-602.66 
























































































































































































































































































































































































M-0 FOR VAPOR AT-460*F ANO 0 PRESSURE 


critical 


POINT 




EMPERATURE-ENTROP 

DIAGRAM 

OF 


NITRpGEN 




:::::::::: 


mm. 


ENTROPY, aiU./LB /OEG. FAHR. 
04 rre nc 


ENTROPY, a T. U./LB./0E6. FAHR 


320 


G-602.67 


351 


TEMPERATURE, 0E6. FAHR 




















































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































352 


G-602.80 


800 900 1000 1100 1200 






















































































































































































































































































































































































































































































































6000 



G-602.90 


353 


-300 -200 -100 0 100 200 300 400 500 600 700 800 900 1000 MOO 1200 1300 1400 1500 






































































































































































































































































































































































































































































































354 


G-603.30 


























































































































































































































































































































































































































































































































































































































































































































G-603.50 


355 


081:_061:_ 003- _013-_ 033- 0€3- _ 0t>3- _ 093- _ 093- _ 0Z3~ _ 083- _ 063- 00C- QIC' 03C' 




























































































































































































































































































































































































































































































































































































































DENSITY 

OF 

ARGON 



356 


G-603.60 




























































































































































































































































































































G-603.80 


357 
































































































































































































































































































































































































































































-400 -300 - 200 -100 _0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 



358 


G-603.90 


-400 -300 -200 -100 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 






































































































































































































































































































































































































































































































































NOTE- 

FOR TEMPERATURES ABOVE 
-50°F SEE PAGE 2 


8ASE‘- 

H«0 FOR VAPOR AT-460*F AND O PRESSURE 


liQL. 


G-605.30—Part 1 


359 













































































































































































































































































































































































































































































ENTHALPY 

OF 

OXYGEN 



360 


G-605.30—Part 2 




































































































































































































































































































s- 88 


o o o 

2 ©N 8 8 § 


8 °° O o o Q O Q 

ao cp in ^ K) ed 


Pen CO h- CD 



IQ O O o O 

Q O O O O 

O CD s CD m 


OOO O O Q o O O 

0<T> CO S CD u) ^ rO cvj 


0(J> oO N- CD *** ^ 


G-605.50 


361 


-310 -300 -290 -280 -270 -260 -250 -240 -230 -220 -210 -200 -190 -180 




















































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































DENSITY 

OF 

OXYGEN 



362 


G-605.60 






























































































































































































































































































































































































































G-605.65 


363 


-280 -260 -240 -220 -200 -180 -160 -140 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180 200 220 240 260 






























































































































































































































































































































































































ENTROPY, BTU/LB/OEG FAHR 



ENTROPY BTU/LB/OEG 


364 


G-605.66 


TEMPERATURE, OEG FAHR 








































































































































































































































































































































































































































































































% P P p p P p II P ilp-? ?^/idOs/;aH/ni9 ‘AiiAiionoNOO nyyjfcOHj. \ $$ p {Kip Hi 

§0 ® <JD 5 .CNJ o 00 00 .V cvj o 00.<jp ^ CJ 0.00 . 

'S 


G-605.80 


365 






































































































































































































































































































































































































































































































366 


G-605.90 


1100 1200 1300 1400 















































































































































































































































































































































































































































G-609.30 


367 
































































































































TEMPERATURE, DEG FAHR. 


ENTROPY. BTU/La/OEG fakr 



r mm 


ENTROPY, BTU/LB/DEG FAHR 


368 


G-609.65 


URE, DEG FAHR 
























































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































ywvj 930 '3dniVb3dK3i 


I 




WHVi 930‘3bfUsrM3drQi 


WMVd «)30*3dru»tf3drGi 


G-609.65 


369 


ENTROPX aiU/LB /OCO f*HR I ENTROPX &TU- 















































































































































































































































































































































































































































































































































































































































































































































































































































































































370 


G-675.30 

































































































































































































































































T EMPERATURE 



G-675.51 


371 


TEMPERATURE 






















































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































DENSITY 

OF 

CARBON DIOXIDE 



di 'o,ooo 


TTfUff 


DENSITY, LBS/CU FT 4 


8000 


8000 


7000 


7000 


4000 


4000 


q. =2896 LBS /CUFT 
\ =eao°F 
8 =1072 PS.I. 


2000 


DENSITY, LBS./CU FT 


400 


300 


: 200 


4 5 6 7 8 9 1 

—XICT*- 1 


800 

700 

600 


5000 


-XIO' 1 


XIO 


372 


G-675.60 



































































































































































































































































































































































G-675.65 


373 
















































































































































































































































































































































































































































TEMPERATURE, DEG. FAHR. 


THERMAL CONDUCTIVITY 
OF 

CARBON DIOXIDE 




-120 -115 -110 -105 -100 -95 -90 -85 -80 -75 -70 -65 -60 -55 


-50 



374 


G-675.80 




















































































































































































































































































































1499,,. ,, . « 12PQ 



■fiSlljili 




gOIX S3SI0dllN30-AllS00SIA 


VISCOSITY 

OF 

CARBON DIOXIDE 


--! 




J; . • • r- -■ 


ainon gaivanivs 


|eOI X S3SIOdliN30-AIISOOSIA 




ttmttmtj 


G-675.90 


375 


-IOO 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 








































































































































































































































































































































































































































































































































376 


G-815.30 
























































































































































































































































































































































































































































B. T. U./LB. 



CQHSTA n? 


per ati 


SATJR Wb W&t 


io 50 sc 

MOL PERCENT OXYGEN 


iKni’ll::::! 




SsSHtoi 


HH 


ill Hi 


BASE- 

OXYGEN- H*0 FOR VAPOR AT -460*F AND 0 PRESSURE 
NITROGEN —H=0 FOR VAPOR AT -460*F AND 0 PRESSURE 


MOL PERCENT OXYGEN 


190 

ISO 

170 

160 

150 

140 

130 

120 

110 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

0 

-10 

-20 

-30 

-40 

-50 


140 


20 


30 


ENTHALPY 

OF 

OXYGEN-NITROGEN MIXTURES 
AT 14.7 L8S/5QNABS. 


G-815.31 


377 


ENTHALPY, a T. U7LB. 








































































































































































































































































































































































































































































ENTHALPY, B.T.U./LB. 


BASE - 

OXYGEN-H=0 FOR VAPOR AT -460°F AND 0 PRESSURE. 
NITROGEN -H-0 FOR VAPOR AT -460°F AND 0 PRESSURE. 


ENTHALPY 
OF 

OXYGEN-NITROGEN MIXTURES 
AT7*5 LBS. / SO. IN. ABS. 



378 


G-815.32 


ENTHALPY, B.T.U./LB. 



















































































































































































































































































ENTHALPY, BTU/LB 


BASE- 

H s 0 FOR VAPOR AT -460°F AND 0 PRESSURE. 


ENTHALPY 

oxygen-nitr8gen MIXTURES 
AT 150 LBS/SQ IN. ABS 



2H CONSTfli 


JUMPER ar i 


^AfuRArEO VAPOR 


SATURATED liquid 


MOL PERCENT OXYGEN 

30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 


190 


40 


1 - .~ “.**... aU " ^... ‘ lOO 

MOL PERCENT OXYGEN 


G-815.33 


379 


ENTHALPY, BTU/LB 




















































































































































































































































































































































































































B.IU/LB 


ENTHALPY-ENTROPY 

DIAGRAM 

OF 

AIR 


ENTROPY BTU/LB/06G FAHR 



380 


G-815.34 


aiu/ia 





















































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































350 



G-815.50 


381 


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382 


G-815.51 


-330 -320 -310 -300 -290 -280 -270 -260 -250 -240 -230 -220 -210 -200 -190 




























































































































































































































































































































































































































































































































G-815.52 


383 
































































































































































































































































































































384 


G-815.53 


































































































































































































































































































































































































































































EQUILIBRIUM 

OF 

OXYGEN-ARGON 
MIXTURES 




G-815.54 


385 























































































































































































































































































































































































































LIQUID-VAPOR 

EQUILIBRIUM 

FOR 

OXYGEN-NITROGEN SYSTEM 



MOL FRACTIONOF OXYGEN IN LIQUID PHASE 


MOL FRACTION OF NITROGEN IN LIQUID PHASE 








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DENSITY 

OF 

AIR 


10,000 



G-815.60 


387 






























































































































































































































































































































































































































340 - 320 -300 -280 -260 -240 -220 -200 -180 -160 -140 -120 -100 - 80 -60 -40 -20 0 20 40 60 80 100 120 



388 


G-815.65 

































































































































































































































































































































































































































































mhvj Oja 'awruvw^ai 



-S.OFWUOUID AT - 5I8*F ( 0 P) AMO 760 MM 

M*0 FOR VAPORAT-«59 7*F AND OMM 
0* CRITICAL POINT 
V -2210*F 


TEMPERATURE-El 
DIAGRAM 
FOR 


ENTROPY. 0 T U /LB /OEG FAHR 


04 05 

ENTROPY. 8 T U /LB./OtO FAMR 


G-815.66 


389 










































































































































































































































































































































































































































































































































































































390 


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1200 

1000 

-4( 


G-815.90 


391 































































































































































































































































































































































































































































VISCOSITY 

OF 

LIQUID NITROGEN-OXYGEN 
MIXTURES_ 



392 


G-815.91 


VISCOSITY-CENTIPOISES-XIO 3 



























































































































































































































































Ambient. 

API. 

ATPD. 

BHP. 

Bottoms. 

BTPS. 

BTU. 

Ce. 

CGSU. 

CFH. 

CFM. 

Chelate compound. 

CL. 

Co. 

Cold box. 

Co-Sal-En. 

Co-x-Sal-En. 

Cp. 

Cv-1, etc. 

C4B, etc. 

En. 

Ethacol. 

Ethomine. 

EtMMgBr. 

Fluomine. 

FPM. 

Frost (dew) point. 
HETP. 

HP. 

HTU. 

ID. 

Joule-Thompson. 

Kcal/mole. 

l/min. 

LP-1. 

LPAS-3. 

LPS-2. 

MeMMgI. 

Methomine. 

mg/l. 

MSA. 

M-2, M-F, etc. 

M-F. 

NBS. 

OD. 

O-Ethovan. 

Overhead. 

Pauling meter. 

PRTN. 

Productivity (P). 

psi. 

psia. 

Reversing exchangers. 

rpm. 

Salcomine. 

Saturation (S). 


GLOSSARY 

Surrounding atmosphere. 

Armor-piercing, incendiary (bullets). 

Air temperature—pressure deviation. 

Brake horsepower. 

That part of the liquid which is drawn off from the lower part of the tower. 

Body temperature pressure saturated. Temperature and pressure under saturated conditions in 
the body. 

British thermal unit. 

Exit concentration. 

Centimeter gram second units. 

Cubic feet per hour. 

Cubic feet per minute. 

An organic compound in which atoms of the same molecule are coordinated. 

Center line. 

Entering concentration. 

That portion of a mechanical oxygen plant containing the fractionation column and low-tempera¬ 
ture heat exchanger equipment. 

Cobalt salicylaldehyde ethylenediamine. 

X-substituted salicylaldehyde ethylenediamine cobalt. 

Specific heat of a gas. 

Refer to control valve No. 1 etc., on flow sheets.. 

Refer to unit parts of the flow sheet. 

Ethylenediamine. 

O-ethoxyphenol. 

Cobalt 3-ethoxy salicylaldehyde ethylenediamine. 

Ethyl magnesium bromide. 

Cobalt 3-fluro salicylaldehyde ethylenediamine. 

Feet per minute. 

The boundary temperature at which ice (water) is deposited upon a surface. 

Height of a packed column equivalent to a theoretical plate. 

Horsepower. 

Height of a transfer unit. 

Inside diameter. 

The change in enthalpy produced by the direct expansion of a gas. 

Kilogram-calorie per mole. 

Liters per minute. 

Low-pressure Model 1. 

Low-pressure air transportable Model 3. 

Low-pressure skid model. 

Methyl magnesium iodide. 

Cobalt 3-methoxy salicylaldehyde ethylenediamine. 

Milligrams per liter. 

Mine Safety Appliance Company (Hopcalite). 

Designation of plants described in Chapters 3 and 4. 

Designation of a low-pressure mechanical method for separation of oxygen from air (Chapter 2). 
National Bureau of Standards. 

Outside diameter. 

3-ethoxysalicylaldehyde. 

That part of the gas which is drawn off from the top of the tower. 

Instrument for determining the magnetic susceptibility of a mixture of gases. 
Bis-trimethylenetriamine. 

Actual amount of oxygen produced under cycling conditions. 

Pounds per square inch gauge pressure. 

Pounds per square inch absolute pressure. 

Multiple pass heat exchanger in which counter current gas streams are switched at intervals 
so that a reversal of flow results in a given pass from period to period. 

Revolutions per minute. 

Salicylaldehyde ethylenediamine cobalt (active form). 

A measure of the amount of the compound present which is capable of absorbing oxygen. 


393 


394 


GLOSSARY 


SCF. 

Schiff’s base. 

S.L. 

Stedman-column. 

STP. 

Switch exchangers. 
Sylphon control. 
TFE. 

Turbulator strip. 


Standard cubic feet—volume at 60 F and 1 atmosphere pressure. 
Condensation product of an aliphatic amine and an aromatic aldehyde. 
Sea level. 

A particular type of fractionation column packing (Chapter 5). 
Standard temperature and pressure. 

Heat exchangers which are switched from one gas stream to another. 
A pressure control device with a metal “sylphon” bellows. 
Tetrafluoroethane. 

A twisted strip inserted in tubing to produce turbulent flow. 



BIBLIOGRAPHY 

Numbers such as Div. 11-101 -M1 indicate that the document listed has been microfilmed and that its title appears 
in the microfilm index printed in a separate volume. For access to the index volume and to the microfilm, consult 
the Army or Navy agency listed on the reverse of the half-title page. 


Chapter 2 

1. Final Report of NDRC Oxygen Reviewing Committee, 
T. R. Chilton, Harry A. Curtis, and others, Dec. 22, 1941. 

Div. 11-101-MI 

2. Small Portable Plants for the Production of Liquid 

Oxygen, Barnett F. Dodge, NDCrc-80, Yale University, 
June 27, 1941. Div. 11-103.1-M2 

3. The Production of Liquid Oxygen, Barnett F. Dodge 
and Harding Bliss, NDCrc-80, Yale University, Aug. 1, 

1941. Div. 11-103.1-M3 

4. Processes for the Manufacture of Liquid Oxygen from 
Air, Harding Bliss, Yale University, Jan. 15, 1942. 

Div. 11-103.1-M4 

5. The Oxygen Program of Section 11.3, including Bi- 

Monthly Report for December 1942 and January 1943 
prepared for a meeting zvith NDRC Reviewing Commit¬ 
tee, Feb. 13, 1943. Div. 11-102-M3 

6. Resume of Oxygen Program, Section 11.1, Jan. 12, 1944. 

7. Information and Diagram of Several Air Separation 

Cycles, Frederick G. Keyes, NDCrc-182, Special Report 
5, MIT, May 16, 1942. Div. 11-103.4-All 

8. Analysis of Lozu Temperature Air Separation and Gas 
Liquefaction Cycles, Report to January 1, 1943, Barnett 
F. Dodge and Harding Bliss, OSRD 1424, OEMsr-232, 
Project NLB-6, Yale University, May 17, 1943. 

Div. 11-103.4-A14 

SUPPLEMENTARY 

9. Portable Oxygen Generating Plant from Navy BuS to 
Director, NRL, Oct. 31, 1942. 

10. Various Oxygen Producing Units, Wolcott Dennis, 

NDCrc-206, Air Reduction Company, Inc., December 
1943. Div. 11-102.1-M5 

11. Conference on Small Oxygen Units, C. C. Furnas, The 
M. W. Kellogg Company, July 13, 1942. 

Div. 11-102.11-All 

12. Comparison of M-2 and MIT Oxygen Producing Units, 
George T. Skaperdas, M. W. Kellogg Company, Oct. 5, 

1942. 

13. Analysis of Liquid Air Rectification Cycles, Roger 
Adams and Harris Al. Chadwell, OSRD 780, OEMsr- 
454, Project NLB-42, Aug. 10, 1942. Div. 11-103.4-M2 

14. The Development of a Low Temperature Engine-Com- 
pressor-Rectifier Unit for the Separation of Oxygen from 
Air, Frederick G. Keyes and S. C. Collins, Sept. 12, 1941. 

Div. 11-102.1-All 

15. Airplane Oxygen Unit, Frederick G. Keyes, NDCrc-182, 

AIIT, June 27, 1942. Div. 11-102.111-MI 

16. Oxygen Producer, Designed and Built by S. C. Collins, 

at Research Laboratory of Physical Chemistry, Freder¬ 
ick G. Keyes, NDCrc-182, Special Report 12, AIIT, 
Sept. 25, 1942. Div. 11-102.111-M2 


17. Instructions for Operating the Mond-Ricardo British 
Oxygen-Gas Producer, Appendix of Memoranda Per¬ 
taining to Its Construction, Servicing, and Maintenance, 
Frederick G. Keyes, AIIT, Sept. 28, 1942. 

Div. 11-102.111-M3 

18. A Brief Comparison of Low Temperature Cycles for 

Producing Liquid Oxygen from Air, Barnett F. Dodge, 
Yale University, Feb. 15, 1942. Div. 11-103.1-M5 

19. Tentative Outline of Program of Experimental Investi¬ 
gations for NDRC & Present Status of This Work, 
Barnett F. Dodge, Mar. 18, 1942. 

20. High-Pressure Liquid Oxygen Plant Origuially Intended 
as Cascade System as Erected by Dr. W. F. Giauque, 

L. S. Twomey, NDCrc-198, University of California, 

Apr. 26, 1944. Div. 11-103.1-AI6 

Chapter 3 

1. The Development of a Loza Temperature Engine-Com- 
pressor-Rcctificr Unit for the Separation of Oxygen from 
Air, Frederick G. Keyes and S. C. Collins, Sept. 12, 1941. 

Div. 11-102.1-MI 

2. Heat Interchangers for Gases, Alternating Flozv Scrub¬ 
ber-Heat Exchanger, S. C. Collins, NDCrc-182, Special 
Reports 2 and 3, MIT, Alar. 9, 1942. Div. 11-104.13-MI 

3. Compressors, Expansion Engine, Interchangers, Recti¬ 
fiers, Frederick G. Keyes, Apr. 15, 1942. 

4. Oxygen Producer, Designed and Built by S. C. Collins 

at Research Laboratory of Physical Chemistry, Frederick 
G. Keyes, Special Report 12, NDCrc-182, MIT, Sept. 25, 

1942. Div. 11-102.111-M2 

5. A Light-Weight, Automatic, Mechanical Generator, S. C. 

Collins and Howard O. McMahon, OSRD 3800, NDCrc- 
182, Service Projects AC-12, NS-116, CE-29, MIT, 

June 19, 1944. Div. 11-102.111-M7 

6. Various Oxygen Producing Units, Monthly Progress 

Report, Walter E. Lobo, M. W. Kellogg Company, 
Mar. 19, 1942. Div. 11-102.1-M2 

7. Some Consideration on the Removal of Water and Car¬ 
bon Dioxide in- Reversing Exchangers, Sept. 3, 1943. 

Div. 11-104.13-M8 

8. The History of the Development of Heat Exchangers 
for Lozv-Prcssurc Mobile Oxygen Units, Walter E. Lobo, 

M. W. Kellogg Company, Oct. 4, 1943. 

Div. 11-104.13-M5 

9. Low-Pressure Mobile Gaseous Oxygen Units Developed 
for NDRC at Olean, N.Y., Clark Brothers Company, 
Inc., and M. W. Kellogg Company, Oct. 29, 1943. 

10. Various Oxygen Producing Units, Walter E. Lobo, M. 
W. Kellogg Company, Alarch 1942 to January 1944. 

Div. 11-102.2-M2 


395 


396 


BIBLIOGRAPHY 


11. Oxygen Plant Development, Walter E. Lobo, OSRD 
4555, OEMsr-365, Service Projects NA-11, NS-115 and 
others, M. W. Kellogg Company, Feb. 28, 1945. 

Div. 11-102-M4 

13. Mechanical Oxygen Generating Units and Related Equip¬ 
ment, J. N. MacKendrick and A. Van Campen, OSRD 
4792, OEMsr-370, Service Projects AC-12, NA-111 and 
others, Clark Brothers Company, Inc., May 15, 1945. 

Div. 11-102.1-M8 

14. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for May 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
3861, OEMsr-934, University of Pennsylvania, July 7, 
1944. Div. 11-101-M7 

15. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for June 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
3972, OEMsr-934, University of Pennsylvania, Aug. 2, 
1944. Div. 11-101-M7 

16. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for July 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
4142, OEMsr-934, University of Pennsylvania, Sept. 19, 
1944. Div. 11-101-M7 

17. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for September 1944, 
J. H. Rushton, Barnett F. Dodge, and W. L. McCabe, 
OSRD 4302, OEMsr-934, University of Pennsylvania. 
Nov. 6, 1944. Div. 11-101-M7 

18. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for January 1945, 

J. H. Rushton, Barnett F. Dodge, and W. L. McCabe, 
OSRD 4732, OEMsr-934, University of Pennsylvania, 
Mar. 3, 1945. Div. 11-101-M7 

19. Methods of Production and Calibration of Combination 

Vapor Pressure and Gas Dial Thermometers, Paul Erb- 
guth and J. G. Aston, OSRD 4780, University of Penn¬ 
sylvania, Jan. 26, 1945. Div. 11-104.2-M5 

20. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for February 1945, 
J. H. Rushton, Barnett F. Dodge, and W. L. McCabe, 
OSRD 4879, OEMsr-934, University of Pennsylvania, 
Mar. 30, 1945. Div. 11-101-M7 

21. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for April 1945, W. L. 
McCabe, OSRD 5153, OEMsr-934, University of Penn¬ 
sylvania, May 31, 1945. Div. 11-101-M7 

22. Final Report of Central Engineering Laboratory, Univer¬ 
sity of Pennsylvania, for the Period March 1943 through 
June 1945, John A. Gofif and Roy W. Banwell, OSRD 
5482, OEMsr-934, Service Projects NLB-42, NA-106, 
and others, University of Pennsylvania, June 30, 1945. 

Div. 11-101-M9 

23. The Oxygen Program of Section 11.3, Including Bi- 

Monthly Report for December 1942 and January 1943 
Prepared for a Meeting with NDRC Reviewing Com¬ 
mittee, Feb. 13, 1943. Div. 11-102-M3 


24. Oxygen Processes, Report to September 1, 1945, OSRD 
5928, NDCrc-206, Service Projects NS-115 and NS-116, 
Air Reduction Company, Inc., Oct. 1, 1945. 

Div. 11-103.3-M8 

SUPPLEMENTARY 

25. Airplane Oxygen 'Unit. Progress Report on the Possi¬ 
bility of Using the Phenomenon of Heat Transmission at 
Lovo Pressures as a Means of Detecting and Determining 
Gaseous Compositions, data obtained by D. A. Williams, 
Aug. 8, 1942. 

26. Conference on Small Oxygen Units, C. C. Furnas, M. 
W. Kellogg Company, July 13, 1942. Div. 11-102.11-M1 

27. Comparison of M-2 and MIT Oxygen Producing Units, 
George T. Skaperdas, M. W. Kellogg Company, Oct. 5, 
1942. 

28. Mobile Oxygen Units Liquid Air Fractionation Systems, 
Walter E. Lobo, M. W. Kellogg Company, Feb. 3, 1943. 

Div. 11-103.4-M3 

29. Various Oxygen Producing Units, Monthly Progress Re¬ 
ports for Period from January 15 to February 15, 1943, 
Walter E. Lobo, M. W. Kellogg Company. 

Div. 11-102.1-M2 

30. Various Oxygen Producing Units, Monthly Progress Re¬ 
port for Period from February 15 to March 15, 1943, 
Walter E. Lobo, M. W. Kellogg Company, Mar. 23, 1943. 

Div. 11-102.1-M2 

31. Various Oxygen Producing Units, Monthly Progress Re¬ 
port for Period from March 15 to April 15, 1943, Walter 
E. Lobo, M. W. Kellogg Company, Apr. 20, 1943. 

Div. 11-102.1-M2 

32. Various Oxygen Producing Units, Monthly Progress Re¬ 
port for Period from April 15 to May 31, 1943, Walter E. 
Lobo, M. W. Kellogg Company, June 6, 1943. 

Div. 11-102.1-M2 

33. Various Oxygen Producing Units, Monthly Progress Re¬ 

port for Period from June 1 to July 1, 1943, Walter E. 
Lobo, M. W. Kellogg Company. Div. 11-102.1-M2 

34. Various Oxygen Producing Units, Monthly Progress Re¬ 
port for Period from July 1 to July 27, 1943, Walter E. 
Lobo, M. W. Kellogg Company. Div. 11-102.1-M2 

35. Report dated November 1, 1943, summarizing the work 
on the M-2R unit at O’Fallon by J. Broadbent. 

36. I’isit to Air Reduction Sales Company, December 15 and 
16, 1943, George T. Skaperdas, December 1943. 

Div. 11-102.1-M6 

37. Approximate Material Specifications for Clark M-7 Mo¬ 
bile Gaseous Oxygen Unit, December 14, 1943. 

38. Process Calculations for 1000 SCFH Clark Mobile Gas¬ 
eous Oxygen Unit M-7, Walter E. Lobo, Dec. 15, 1943. 

39. Performance of M-7 AT Radiators, Eugene Miller, M. 
W. Kellogg Company, Apr. 16, 1945. 

Div. 11-102.141-M13 

40. Report Covering Consulting Services of Dr. Howard O. 

McMahon to E. B. Badger & Sons Company in Connec¬ 
tion until Mechanical Oxygen Generators, T. L. Wheeler 
and Howard O. McMahon, Arthur D. Little, Inc., Mar. 
6, 1944. Div. 11-102.1-M7 




BIBLIOGRAPHY 


397 


41. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for Period Beginning 
1943 to January 31, 1944, J. H. Rushton, Barnett F. 
Dodge, and others, University of Pennsylvania. 

Div. 11 -101 - M 7 

42. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for February 1944, 
J. H. Rushton and Barnett F. Dodge, OSRD 3523, 
OEMsr-934, University of Pennsylvania, Apr. 25, 1944. 

Div. 11-101-M7 

43. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for March 1944, J. H. 
Rushton and Barnett F. Dodge, OSRD 3652, OEMsr-934, 
University of Pennsylvania, May 19, 1944. 

Div. 11-101-M7 

44. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for April 1944, J. H. 
Rushton and W. L. McCabe, OSRD 3760, OEMsr-934, 
University of Pennsylvania, June 9, 1944. 

Div. 11-101-M 7 

45. The Collins Automatic Airborne Low-Pressure Oxygen 

Unit, D. C. Reams, Jr., Central Engineering Laboratory, 
June 5, 1944. Div. 11-102.111-M6 

46. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for August 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
4207, OEMsr-934, University of Pennsylvania. 

Div. 11-101-M7 

47. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for October 1944, J. D. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
4452, OEMsr-934, University of Pennsylvania. 

Div. 11-101-M7 

48. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for November 1944, 
J. R. Rushton, Barnett F. Dodge, and W. L. McCabe, 
OSRD 4516, OEMsr-934, University of Pennsylvania. 

Div. 11-101-M7 

49. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for December 1944, 
J. H. Rushton, Barnett F. Dodge, and W. L. McCabe, 
OSRD 4623, OEMsr-934, University of Pennsylvania. 

Div. 11-101-M7 

50. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for March 1945, W. L. 
McCabe, OSRD 5040, University of Pennsylvania. 

Div. 11-101-M7 

51. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for April 1945, W. L. 
McCabe, OSRD 5153, University of Pennsylvania. 

Div. 11-101-M7 

52. Progress Report November 15 to December 31, 1943, 
Semi-Portable Oxygen Unit M-6 Expander and Unit, 
Wolcott Dennis. 

53. Report of All Work Done up to June 1, 1942, Toward the 
Dez’clopmcnt of: (a) Large Shipboard Oxygen Liquid 
Unit 4000 Lb/Hr; (b) Small Portable Gas Unit 300 
Cu Ft/Hr, Wolcott Dennis. 


54. Portable Oxygen Generating Plant Requirements from 
Navy BuShips to Director, NRL, Oct. 31, 1942. 

55. Resume of Oxygen Program, Section 11.1, NDRC, Jan. 
12, 1944. 

56. Mobile Oxygen-Nitrogen Generating Units, #TM5-355. 
Technical Manual, U.S. War Department, Jan. 14, 1944. 

Div. 11-102.12-M7 

57. Minutes of Meeting on Field Generation of Oxygen Held 
in Pentagon Bldg., Washington, D.C., April 16, 1943, 
from Maj. Gen. C. C. Williams. 

58. Oxygen Units under Development by the NDRC, S. S. 

Prentiss, Jan. 1, 1943. Div. 11-101-M6 

59. The Oxygen Technical Committee, Morning Meeting, 

Aug. 20, 1942. Div. 11-101-M4 

60. Oxygen Units under Development by the NDRC, S. S. 

Prentiss, Aug. 14, 1942. Div. 11-101-M5 

61. Aircraft Mechanical Oxygen Generator, Howard O. 
McMahon, June 15, 1944. 

62. Submarine Propulsion Committee, Minutes of First Meet¬ 
ing Held at Admiralty, December 1, 1936. 

63. Closed Cycle Operating Characteristics of a Diesel En¬ 
gine, L. F. Campbell, W. E. Whybrew, and W. H. San¬ 
ders, NRL Report #0-2205, December 1943. 

64. Some letters from S. C. Collins to E. P. Stevenson re¬ 
porting on Collins’ work. 

Chapter 4 

1. Final Report of NDRC Oxygen Reviewing Committee, 

T. R. Chilton, Harry A. Curtis, and others, Dec. 22, 
1941. Div. 11-101-MI 

2. Oxygen Producing Units: (1) for Liquefied Oxygen 
Adapted for the Application of Precooling by Standard 
Freon 12 Refrigerating Machines; and (2) Shipboard 
Unit until Rectifier Having Rotating Packing, Frederick 
G. Keyes, Dec. 17, 1943. 

3. Oxygen Generating Equipment, Report to June 30, 1945, 
Frederick G. Keyes, OSRD 5329, NDCrc-182, NA-111, 
NS-115, and others, MIT, July 17, 1945. Div. 11-102-M5 

4. Development and Production of Keyes Type Liquid Oxy¬ 
gen Producers, Final Report for the Period Feb. 1, 1943, 
to Mar. 31,1944, A. C. Shuart, Servel, Inc., June 15, 1944. 

Div. 11-103.3-M7 

5. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for February 1944, 
J. H. Rushton and Barnett F. Dodge, OSRD 3523, 
OEMsr-934, University of Pennsylvania, Apr. 25, 1944. 

Div. 11-101-M7 

6. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for March 1944, J. H. 
Rushton and Barnett F. Dodge, OSRD 3652, OEMsr- 
934, University of Pennsylvania, May 19, 1944. 

Div. 11-101-M7 

7. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for June 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
3972, OEMsr-934, University of Pennsylvania, Aug. 2, 
1944. Div. 11-101-M7 



398 


BIBLIOGRAPHY 


8. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for December 1944, 
J. H. Rushton, Barnett F. Dodge, and W. L. McCabe, 
OSRD 4623, OEMsr-934, University of Pennsylvania. 

Div. 11-101-M7 

9. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for January 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
4732, OEMsr-934, University of Pennsylvania. 

* Div. 11-101-M7 

10. Final Report of the Central Engineering Laboratory, 
NDRC, Section 11.1, Oxygen, for March 1943 through 
June 1945, John A. Goff and Roy W. Banwell, OSRD 
5482, OEMsr-934, NLB-42, NA-106, and others, Uni¬ 
versity of Pennsylvania, June 30, 1945. Div. 11-101-M9 

11. The Joulc-Thomson Type Liquid Oxygen Unit (Sup¬ 
plement 1), T. L. Wheeler and Allen Latham, Jr., 
OEMsr-269, Arthur D. Little, Inc., June 16, 1943. 

Div. 11-103.3-M3 

12. Shipboard Liquid Oxygen Units, Report to Feb. 3, 1944, 

T. L. Wheeler and Allen Latham, Jr., OSRD 3369, 
OEMsr-269, NA-111, NS-115, Arthur D. Little, Inc., 
Apr. 6, 1944. Div. 11-103.3-M6 

13. Outline of Proposed Low-Temperature Trailer-Mounted 
Oxygen Unit for NDRC, W. F. Giauque, NDCrc-198, 
University of California, June 15, 1942. 

Div. 11-102.12-M2 

14. Clark 4-Stage, 3,000-psi Compressor Used in Liquid Oxy¬ 

gen Trailer Unit, W. F. Giauque, NDrc-198, University 
of California, Jan. 27, 1944. Div. 11-102.141-M10 

15. Liquid Oxygen Trailer Unit Report to July 25, 1944. 

W. F. Giauque, NDCrc-198, OSRD 4141, University of 
California, Sept. 19, 1944. Div. 11-103.1-M7 

16. Portable Compressor Program Progress Report to Noy. 
30, 1942, Clark Brothers Company, Inc., December 1942. 

Div. 11-102.141-M5 

17. Letter to Earl P. Stevenson, Subject: Portable Compres¬ 
sor Program (includes Elliott Technical Report on Test¬ 
ing of the 200 CFM Elliott-Lysholm Two-Stage Com¬ 
pressor, Dated December 9, 1943), J. N. MacKendrick 
and A. Van Campen, June 1, 1944. 

Div. 11-102.141-M12, Div. 11-102.141-M9 

18. Mechanical Oxygen Generating Units & Related Equip¬ 
ment, J. N. MacKendrick and A. Van Campen, OSRD 
4792, Clark Brothers Company, Inc., May 15, 1945. 

Div. 11-102.1-M8 

19. Oxygen Plant Development Report to February 28, 1945, 

Walter E. Lobo, OSRD 4555, M. W. Kellogg Co., Feb. 
28, 1945. Div. 11-102-M4 

20. Oxygen Plant 350-450 CFH Gas or Liquid Production, 
Wolcott Dennis, June 15, 1943. 

21. Portable Oxygen Unit No. MH-400-AC (NS-116), Wol¬ 
cott Dennis, Jan. 27, 1943. 

22. Oxygen Processes Report to Sept. 1, 1945, OSRD 5928, 
Air Reduction Co., Inc., Oct. 1, 1945. Div. 11-103.3-M8 

23. Report on Akcrman Liquid Oxygen Converter, Washing¬ 
ton File A-906, Submitted by BuS, Navy Dept., Wash¬ 
ington, D.C., on Feb. 16, 1943, (May 19, 1943). 


SUPPLEMENTARY 

24. Various Oxygen Producing Units Progress Report on 
NDRC Contract No. NDCrc-206 with the Air Reduction 
Co., for Period Nov. 15-Dec. 31, 1943, Wolcott Dennis, 
Air Reduction Co., Inc., December 1943. 

Div. 11-102.1-M5 

25. Skid Mounted Oxygen Plant, Progress Report on NDRC 

Contract No. NDCrc-206, Wolcott Dennis, Air Reduc¬ 
tion Co., Nov. 15, 1943. Div. 11-102.12-M5 

26. Various Oxygen Producing Units Monthly Report, Wol¬ 
cott Dennis, Air Reduction Co., October 1942. 

Div. 11-102.1-M4 

27. Monthly Report for Various Oxygen Producing Units, 
Wolcott Dennis, Air Reduction Co., September 1942. 

Div. 11-102.1-M4 

28. Monthly Report for Various Oxygen Producing Units, 
Wolcott Dennis, Air Reduction Co., August 1942. 

Div. 11-102.1-M4 

29. Monthly Report for Various Oxygen Producing Units, 
Wolcott Dennis, Air Reduction Co., July 1942. 

Div. 11-102.1-M4 

30. Monthly Report for Various Oxygen Producing Units, 

Wolcott Dennis, Air Reduction Co., June 1942 (dated 
July 2, 1942). Div. 11-102.1-M4 

31. Report of All Work Done up to June 1, 1942, Toward 
the Development of: (a) Large Shipboard Oxygen Liquid 
Unit 4,000 Lbs/Hr; (b) Small Portable Gas Unit 300 
Cu Ft /Hr, Wolcott Dennis, Air Reduction Co. 

32. Report on Tests on Oxygen Rectification Equipment to 
Feb. 12, 1942, S. S. Prentiss, OSRD 450. 

>33. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report Covering Period from 
1943 to Jan, 31, 1944, J. H. Rushton, University of Penn¬ 
sylvania. Div. 11-101-M7 

34. Processes for the Removal of Carbon Dioxide from the 
Atmosphere of a Submarine, Allan P. Colburn and Bar¬ 
nett F. Dodge, University of Pennsylvania, Feb. 20, 1944. 

Div. 11-105.22-M3 

35. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progess Report for April 1944, J. H. 
Rushton and W. L. McCabe, OSRD 3760, University of 
Pennsylvania, June 9, 1944. Div. 11-101-M7 

36. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for May 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
3861, University of Pennsylvania, July 7, 1944. 

Div. 11-101-M7 

37. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for July 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
4142, University of Pennsylvania, Sept. 19, 1944. 

Div. 11-101-M7 

38. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for August 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
4207, University of Pennsylvania, Oct. 6, 1944. 

Div. 11-101-M7 




BIBLIOGRAPHY 


399 


39. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for September 1944, 
J. H. Rushton, W. L. McCabe, and Barnett F. Dodge, 
OSRD 4302, University of Pennsylvania, Nov. 6, 1944. 

Div. 11-101-M7 

40. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for October 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
4452 University of Pennsylvania, Dec. 13, 1944. 

Div. 11-101-M7 

41. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for November 1944, 
J. H. Rushton, Barnett F. Dodge, and W. L. McCabe, 
OSRD 4516, University of Pennsylvania, Dec. 30, 1944. 

Div. 11-101-M7 

42. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for February 1945, 
J. H. Rushton, Barnett F. Dodge, and W. L. McCabe, 
OSRD 4879, University of Pennsylvania, Mar. 30, 1945. 

Div. 11-101-M7 

43. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for March 1945, W. L. 
McCabe, OSRD 5040, University of Pennsylvania, Apr. 

30, 1945. Div. 11-101-M7 

44. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for April 1945, W. L. 
McCabe, OSRD 5153, University of Pennsylvania, May 

31, 1945. Div. 11-101-M7 

45. Conference on Small Oxygen Units, C. C. Furnas, M. W. 
Kellogg Company, July 13, 1942. Div. 11-102.11-MI 

46. Comparison of M-2 and MIT Oxygen Producing Units, 
George T. Skaperdas, Oct. 5, 1942. 

47. Mobile Oxygen Units Liquid Air Fractionation Systems, 
Walter E. Lobo, M. W. Kellogg Company, Feb. 3, 1943. 

Div. 11-103.4-M3 

48. Observation of Air Reduction in NDRC Skid Unit on 
December 6, 1943, George T. Skaperdas, December 1943. 

Div. 11-102.12-M6 

49. The Development of a Low-Temperature Engine Com¬ 

pressor Rectifier Unit for the Separation of Oxygen from 
Air. Frederick G. Keyes and S. C. Collins, Sept. 12, 

1941. Div. 11-102.1-MI 

50. Airplane Oxygen Unit, Frederick G. Keyes, NDCrc-182, 

MIT, June 27, 1942. Div. 11-102.111-MI 

51. Report on Airplane Oxygen Unit, Progress Report on 
the Possibility of Using the Phenomenon of Heat Trans¬ 
mission at Low Pressures as a Means of Detecting and 
Determining Gaseous Compositions, data obtained by D. 
A. Williams, Aug. 8, 1942. 

52. Instructions for Operating the Mond-Ricardo British 
Oxygen-Gas Producer, Appendix of Memoranda Pertain¬ 
ing to Its Construction, Servicing, and Maintenance, 
Frederick G. Keyes, MIT, Sept. 28, 1942. 

Div. 11-102.111-M3 


54. Operating Instructions for MIT Model S-Unit for Pro¬ 
ducing Liquefied Oxygen for Respiratory Use on Sub¬ 
marines and Other Purposes, prepared by D. A. Williams, 
submitted by Frederick G. Keyes, Mar. 24, 1944. 

55. Report of Progress under Contract OEMsr-654, J. F. 
Pritchard, J. F. Pritchard Company, Dec. 14, 1942. 

Div. 11-103.3-M2 

56. Instrument Instructions—Liquid Oxygen Plant — M-6, 
J. F. Pritchard Company. 

57. Production Progress of Oxygen Producing Unit, Monthly 
Report from March 15 to April 15, 1943, R. R. Enders, 
NDCrc-830, Servel, Inc., April 1943. Div. 11-101-M8 

58. Report on Liquid Oxygen, May 1 to June 30, 1941, W. F. 
Giauque, University of California. 

59. Informal Comments Requested by the M. IV. Kellogg 

Co. on Provisional Design of Oxygen Units, W. F. 
Giauque, NDCrc-198, University of California, May 15, 

1942. Div. 11-102.12-MI 

60. Instructions and Flow Sheet for Giauque Unit, in letter 
to J. H. Rushton from W. F. Giauque, Apr. 28, 1944. 

61. Review of Oxygen Program for 1942, Including Bi- 
Monthly Report for Dec. 1942 and Jan. 1943, for meet¬ 
ing with NDRC Reviewing Committee, Feb. 13, 1943. 

62. Resume of Oxygen Program, Section 11.1, NDRC, Jan. 
12, 1944. 

63. Minutes of Meeting on Field Generation of Oxygen Held 
in Pentagon Bldg., Washington, D.C., Apr. 16, 1943, from 
Maj. Gen. C. C. Williams. 

64. Oxygen Units under Development by the NDRC, S. S. 

Prentiss, Jan. 1, 1943. Div. 11-101-M6 

65. The Oxygen Technical Committee Meeting, Aug. 20, 

1942. Div. 11-101-M4 

66. Oxygen Units under Development by the NDRC, S. S. 

Prentiss, Aug. 14, 1942. Div. 11-101-M5 

67. Information on the Mark I Mond Oxygen Separator, Let¬ 

ter from T. R. Hogness to H. M. Chadwell, Washington 
File B-12134, Aug. 5, 1942. 

68. Abstract of Description and Tests on Mond-Ricardo Oxy¬ 
gen Plant, March 1942. 

69. Experimental Small Oxygen Compressor, Report No. 
1207, Washington File B-3833, Ricardo & Co., Oct. 21, 

1943. 

70. Underground Oxygen Plant Located at Wittring, France, 
Washington File B-4791, Mar. 21, 1945. 

71. German Liquid Oxygen Plant at Liege, Oct. 5, 1944. 

Chapter 5 

1. Letter to C. C. Furnas, Subject: Portable Compressor 
Program Progress Report for Period from Early Feb¬ 
ruary to April 15, 1942, J. N. MacKendrick, Clark 
Brothers Company, Inc., April 15, 1942. 

Div. 11-102.141-MI 

2. Letter to C. C. Furnas, Subject: Portable Compressor 

Program Progress Report for Period April 15 to May 15, 
1942, J. N. MacKendrick, Clark Brothers Company, Inc., 
May 15, 1942. Div. 11-102.141-M2 


53. Liquid Oxygen Pump, Frederick G. Keyes, NDCrc-182, 
MIT, Nov! 17, 1943. Div. 11-103.2-M2 



400 


BIBLIOGRAPHY 


3. Letter to C. C. Furnas, Subject: Portable Compressor 

Program, J. N. MacKendrick, Clark Brothers Company, 
Inc., Sept. 19, 1942. Div. 11-102.141-M4 

4. Portable Compressor Program Progress Report to No¬ 

vember 30, 1942, Clark Brothers Company, Inc., Decem¬ 
ber 1942. Div. 11-102.141-MS 

5. Letter to Earl P. Stevenson, Subject: Portable Compres¬ 
sor Program, J. N. MacKendrick and A. Van Campen, 
Clark Brothers Company, Inc., June 1, 1943. 

Div. 11-102.141-M6 

6. Letter to Earl P. Stevenson, Subject: Portable Compres¬ 
sor Program, J. N. MacKendrick and A. Van Campen, 
Clark Brothers Company, Inc., July 20, 1943. 

Div. 11-102.141-M7 

7. Letter to Earl P. Stevenson, Subject: Portable Compres¬ 
sor Program, J. N. MacKendrick and A. Van Campen, 
Clark Brothers Company, Inc., Sept. 25, 1943. 

Div. 11-102.141-M8 

8. Clark Two-Stage 5"x3"x3 l / 2 " Dri-Oxygen Compressor, 
Clark Brothers Company, Inc., Oct. 15, 1943. 

Div. 11-102.142-MI 

9. Letter to Earl P. Stevenson, Subject: Portable Compres¬ 

sor Program (includes Elliott Mechanical Report on 
Testing of the 200 CFM Elliott-Lysholm Two-Stage 
Compressor, dated Dec. 9, 1943), J. N. MacKendrick and 
A. Van Campen, Clark Brothers Company, Inc., June 1, 
1944. Div. 11-102.141-M12, Div. 11-102.141-M9 

10. Letter to Earl P. Stevenson, Subject: Portable Compres¬ 
sor Program, J. N. MacKendrick and A. Van Campen, 
Clark Brothers Company, Inc., Feb. 15, 1944. 

Div. 11-102.141-Mil 

11. Mechanical Oxygen Generating Units and Related Equip¬ 
ment, J. N. MacKendrick and A. Van Campen, OSRD 
4792, Clark Brothers Company, Inc., May 15, 1945. 

Div. 11-102.1-M8 

12. Progress Report, Walter E. Lobo, Clark Brothers Com¬ 
pany, Inc., March 19, 1942, 

13. Progress Report, September 29 to November 11, 1943, 
Walter E. Lobo, Clark Brothers Company, Inc., Nov. 18, 

1943. 

14. Progress Report, November 11 to December 31, 1942, 
Walter E. Lobo, Clark Brothers Company, Inc., Jan. 3, 

1944. 

15. Oxygen Plant Development—Report to February 28, 

1945. Walter E. Lobo, OSRD 4555, M. W. Kellogg Com¬ 
pany, Feb. 28, 1945. Div. 11-102-M4 

16. First Progress Report, Yale University, Small Portable 
Plants for the Production of Liquid Oxygen, June 14, 

1941, Barnett F. Dodge, Dodge Serial No. 45, issued 
June 27, 1941. 

17. The Production of Liquid Oxygen, Barnett F. Dodge and 
Harding Bliss, NDCrc-80, Yale University, Aug. 1, 1941. 

Div. 11-103.1-M3 

18. Letter to S. S. Prentiss, Subject: Expander Casing and 
Compressor, J. R. McDermet, Elliott Company, Aug. 7, 

1942. Div. 11-102.13-M2 


19. The Development of 1700-CFM Lozu Temperature Ex¬ 

pander, Progress Report for Period July 1 to August 15, 
1942, Judson S. Swearingen, Elliott Company, Aug. 19, 
1942. Div. 11-102.13-MI 

20. The Development of 1700-CFM Loiv Temperature Ex¬ 

pander, Progress Report for Period August 16 to Sep¬ 
tember 15, 1942, Judson S. Swearingen, Elliott Company, 
Sept. 16, 1942. Div. 11-102.13-MI 

21. Small Hapeg Compressors, Report No. 14, Judson S. 
Swearingen, Elliott Company, Sept. 19, 1942. 

Div. 11-102.141-M3 

22. Development of 1700-CFM Low Temperature Expander 

for M-5 Unit, Feb. 15 to Mar. 15, 1943, Judson S. 
Swearingen, Elliott Company. Div. 11-102.13-MI 

23. The Development of a Low Temperature Engine-Com¬ 

pressor-Rectifier Unit for the Separation of Oxygen 
from Air, Frederick G. Keyes and S. C. Collins, Sept. 
12,1941. Div. 11-102.1-MI 

24. Special Report No. 4, Compressors, Expansion Engine. 
Interchangcrs, Rectifiers, F. G. Keyes, Apr. 15, 1942. 

25. A Light-Weight, Automatic, Mechanical Oxygen Gen¬ 

erator Issued June 19, 1944, S. C. Collins and Howard O. 
McMahon, May 31, 1944. Div. 11-102.111-M7 

26. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for March 1944, J. H. 
Rushton and Barnett F. Dodge, OSRD 3652, University 
of Pennsylvania. Div. 11-101-M7 

27. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for April 1944, J. H. 
Rushton and W. L. McCabe, OSRD 3760, University of 
Pennsylvania, June 9, 1944. Div. 11-101-M7 

28. Central Engineering Laboratory, NDRC, Section 11-1, 
Oxygen Monthly Progress Report for June 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
3972, University of Pennsylvania, Aug. 2, 1944. 

Div. 11-101-M7 

29. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Jieport for July 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
4142, University of Pennsylvania, Sept. 19, 1944. 

Div. 11-101-M7 

30. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for October 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
4452, University of Pennsylvania, Dec. 13, 1944. 

Div. 11-101-M7 

31. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for December 1944, 
J. H. Rushton, W. L. McCabe, and Barnett F. Dodge, 
OSRD 4623, University of Pennsylvania, Jan. 24, 1945. 

Div. 11-101-M7 

32. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for January 1945, 
J. H. Rushton, W. L. McCabe, and Barnett F. Dodge, 
OSRD 4732, University of Pennsylvania, Mar. 3, 1945. 

Div. 11-101-M7 



BIBLIOGRAPHY 


401 


33. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for March 1945, W. L. 
McCabe. OSRD 5040, University of Pennsylvania. Apr. 
30, 1945. Div. 11-101-M7 

34. Final Report of Central Engineering Laboratory, Uni¬ 
versity of Pennsylvania for Period March 1943 through 
June 30, 1945, John A. Goff and Roy W. Batiwell, OSRD 
5482, University of Pennsylvania, June 30, 1945. 

Div. 11-101-M9 

35. Clark Four-Stage, 3000-psi Compressor used in Liquid 
Oxygen Trailer Unit, W. F. Giauque, NDCrc-198, Uni¬ 
versity of California, Jan. 27, 1944. 

Div. 11-102.141-M10 

36. Liquid Oxygen Trailer Unit, Report to July 25, 1944, 

W. F. Giauque, NDCrc-198, OSRD 4141, University of 
California, Sept. 19, 1944. Div. 11-103.1-M7 

37. Tests of Performance of the Collins-Type Expansion 

Engine Built by Clark Bros. Co., Inc., Report to Jan. 
26, 1944, J. G. Ashton, OSRD 3482, Pennsylvania State 
College, Apr. 14, 1944. Div. 11-102.13-M3 

38. Oxygen Processes, OSRD 5928, Air Reduction Co., 
Oct. 1, 1945. 

SUPPLEMENTARY 

39. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for 1943 to Jan. 21, 
1944, J. H. Rushton, University of Pennsylvania. 

Div. 11-101-M7 

40. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for February 1944, 
J. H. Rushton and Barnett F. Dodge, OSRD 3523, Uni¬ 
versity of Pennsylvania, Apr. 25, 1944. Div. 11-101-M7 

41. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for May 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
3961, University of Pennsylvania, July 7, 1944. 

Div. 11-101-M7 

42. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for September 1944, 
J. H. Rushton, Barnett F. Dodge, and W. L. McCabe, 
OSRD 4302, University of Pennsylvania, Nov. 6, 1944. 

Div. 11-101-M7 

43. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for February 1945, 
J. H. Rushton, W. L. McCabe, and Barnett F. Dodge, 
OSRD 4879, University of Pennsylvania, Mar. 30, 1945. 

Div. 11-101-M7 

44. The Development of 1700-CFM Low Temperature Ex¬ 
pander, Monthly Progress Report for Sept. 16 to Oct. 

15, 1942, Judson S. Swearingen, Elliott Company, Oct. 

16, 1942. Div. 11-102.13-MI 

45. The Development of 1700-CFM Love Temperature Ex¬ 

pander, Monthly Progress Report for October 15 to 
November 15, 1942, Judson S. Swearingen, Elliott Com¬ 
pany, Nov. 18, 1942. Div. 11-102.13-MI 

46. The Development of 1700-CFM Loza Temperature Ex¬ 

pander, Monthly Progress Report for November 16 to 
December 15, 1942, Judson S. Swearingen, Elliott Com- 
D anv. Div. 11-102.13-MI 


47. The Development of 1700-CFM Low Temperature Ex¬ 
pander, Monthly Progress Report for Dec. 15, 1942 to 
Jan. 15, 1943, Judson S. Swearingen, Elliott Company. 

Div. 11-102.13-MI 

48. The Development of 1700-CFM Love Temperature Ex¬ 
pander, Monthly Progress Report for Jan. 15 to Feb. 15, 
1943, Judson S. Swearingen, Elliott Company. 

Div. 11-102.13-MI 

49. The Development of 1700-CFM Low Temperature Ex¬ 
pander, Monthly Progress Report for Mar. 15 to Apr. 15, 
1943, Judson S. Swearingen, Elliott Company. 

Div. 11-102.13-MI 

50. The Development of 1700-CFM Love Temperature Ex¬ 
pander, Monthly Progress Report for Apr. 15 to May 15, 
1943, Judson S. Swearingen, Elliott Company. 

Div. 11-102.13-MI 

51. The Development of 1700-CFM Lozv Temperature Ex¬ 
pander, Monthly Progcss Report for May 15, 1943 to 
June 15, 1943, Judson S. Swearingen, Elliott Company. 

Div. 11-102.13-MI 

52. The Development of 1700-CFM Lozv Temperature Ex¬ 

pander, Monthly Progress Report for June 15 to July 
15, 1943, Judson S. Swearingen, Elliott Company, July 
23, 1943. Div. 11-102.13-MI 

53. The Development of 1700-CFM Lozv Temperature Ex¬ 

pander, Monthly Progress Report, Aug. 15 to Sept. 15, 
1943, Judson S. Swearingen, Elliott Company, Sept. 22, 
1943. Div. 11-102.13-MI 

54. The Development of 1700-CFM Lozv Temperature Ex¬ 

pander, Monthly Progress Report, Sept. 15 to Oct. 15, 
1943, Judson S. Swearingen, Elliott Company, Oct. 22, 
1943. Div. 11-102.13-MI 

55. The Development of 1700-CFM Low Temperature Ex¬ 

pander, Monthly Progress Report, Oct. 15 to Nov 15, 
1943, Judson S. Swearingen, Elliott Company, Nov. 22, 
1943. Div. 11-102.13-MI 

56. The Development of 1700-CFM Low Temperature Ex¬ 

pander, Monthly Progress Report, Nov. 15, 1943 to Dec. 
15, 1943, Judson S. Swearingen, Elliott Company, Dec. 
21, 1943. Div. 11-102.13-MI 

57. Various Oxygen Producing Units, Monthly Progress 

Report for Apr. 23, 1942, Walter E. Lobo, M. W. Kel¬ 
logg Co. Div. 11-102-MI 

58. Various Oxygen Producing Units, Monthly Progress 

Report for May 15, 1942, Walter E. Lobo, M. W. Kel¬ 
logg Co. Div. 11-102-MI 

59. Various Oxygen Producing Units, Monthly Progress 

Report for June 15 to July 15, 1942, Walter E. Lobo, 
M. W. Kellogg Co. Div. 11-102-MI 

60. Various Oxygen Producing Units, Monthly Progress 

Report for July 15 to Aug. 15, 1942, Walter E. Lobo, 
M. W. Kellogg Co. Div. 11-102-MI 

61. Various Oxygen Producing Units, Monthly Progress 

Report for Aug. 15 to Sept, 15, 1942, Walter E. Lobo, 
M. W. Kellogg Co. Div. 11-102-MI 

62. Various Oxygen Producing Units, Monthly Progress 

Report for Sept. 15 to Oct. 15, 1942, Walter E. Lobo, 
M. W. Kellogg Co. Div. 11-102-MI 



402 


BIBLIOGRAPHY 


63. Various Oxygen Producing Units, Monthly Progress 

Report for Oct. 15 to Nov. 15, 1942, Walter E. Lobo, 
M. W. Kellogg Co. Div. 11-102-MI 

64. Various Oxygen Producing Units, Monthly Progress 

Report for Nov. 15 to Dec. 15, 1942, Walter E. Lobo, 
M. W. Kellogg Co. Div. 11-102-MI 

65. Various Oxygen Producing Units, Monthly Progress 

Report for Dec. 15, 1942 to Jan. 15, 1943, Walter E. 
Lobo, M. W. Kellogg Co. Div. 11-102-MI 

66. Mobile Oxygen Units Liquid Air Fractionation Sys¬ 

tems, Walter E. Lobo, M. W. Kellogg Company, Feb. 
3, 1943. Div. 11-103.4-M3 

67. Various Oxygen Producing Units, Monthly Progress 

Report for Jan. 15 to Feb. 15, 1943, Walter E. Lobo, 
M. W. Kellogg Co. Div. 11-102-MI 

68. Various Oxygen Producing Units, Monthly Progress 

Report for Feb. 15 to Mar. 15, 1943, Walter E. Lobo, 
M. W. Kellogg Co. Div. 11-102-MI 

69. Various Oxygen Producing Units, Monthly Progress 

Report for Mar. 15 to Apr. 15, 1943, Walter E. Lobo, 
M. W. Kellogg Company. Div. 11-102.1-M2 

70. Various Oxygen Producing Units, Monthly Progress 

Report for Apr. 15 to May 31, 1943, Walter E. Lobo, 
M. W. Kellogg Co. Div. 11-102.1-M2 

71. Various Oxygen Producing Units, Monthly Progress 

Report for June 1 to July 1, 1943, Walter E. Lobo, 
M. W. Kellogg Company. Div. 11-102.1-M2 

72. Various Oxygen Producing Units, Monthly Progress 

Report for July 1 to 27, 1943, Walter E. Lobo, M. W. 
Kellogg Company. Div. 11-102.1-M2 

73. Various Oxygen Producing Units, Monthly Progress 

Report for July 27 to Aug 26, 1943, Walter E. Lobo, 
M. W. Kellogg Company. Div. 11-102.1-M2 

74. Various Oxygen Producing Units, Monthly Progress 

Report for Aug. 27 to Sept. 28, 1943, Walter E. Lobo, 
M. W. Kellogg Company. Div. 11-102.1-M2 

75. Low-Pressure Mobile Gaseous Oxygen Units Developed 
for NDRC at Olcan, N.Y., Clark Bros. Co. Inc., and the 
M. W. Kellogg Co., Oct. 29, 1943. Div. 11-102.12-M4 

76. Report dated November 1, 1943, summarizing the work 
on the M-2R unit at O’Fallon, J. Broadbent. 

77. Performance of M-7AT Radiators, Eugene Miller, 
M. W. Kellogg Company, Apr. 16, 1945. 

Div. 11-102.141-M13 

Chapter 6 

1. Progress Report, Clark Bros. Co., Inc., Portable Com¬ 
pressor Program, to C. C. Furnas from J. N. MacKen- 
drick, December 24, 1942. 

2. Mechanical Oxygen Generating Units and Related Equip¬ 
ment, J. N. MacKendrick and A. Van Campen, OSRD 
4792, Clark Bros. Co., Inc., May 15, 1945. 

Div. 11-102.1-M8 

3. Liquid Oxygen Pump and Vaporizer, Report to May 15, 
1945, T. L. Wheeler and Allen Latham, Jr., OSRD 5152, 
Arthur D. Little, Inc., May 31, 1945. Div. 11-103.2-M3 


4. Liquid Oxygen Pump, Frederick G. Keyes, NDCrc-182, 

MIT, Nov. 17, 1943. Div. 11-103.2-M2 

5. A Light-Weight, Automatic, Mechanical Oxygen Gen¬ 
erator, Report to May 31, 1944, S. C. Collins and How¬ 
ard O. McMahon, OSRD-3800, MIT, June 19, 1944. 

Div. 11-102.111-M7 

6. Oxygen Generating Equipment, Report to June 30, 1945, 

Frederick G. Keyes, OSRD-5329, NDCrc-182, MIT, 
July 17, 1945. Div. 11-102-M5 

7. Final Report of Central Engineering Laboratory, Uni¬ 
versity of Pennsylvania, for Period from March 1943 
through June 1945, John A. Goff and Roy W. Banwell, 
OSRD 5482, University of Pennsylvania, June 30, 1945. 

Div. 11-101-M9 

8. Liquid Oxygen Trailer Unit, Report to July 25, 1944, 

W. F. Giauque, OSRD 4141, NDCrc-198, University of 
California, Sept. 19, 1944. Div. 11-103.1-M7 

Chapter 7 

1. Some Consideration on the Removal of Water and Car¬ 
bon Dioxide in Reversing Exchangers, Sept. 3, 1943. 

Div. 11-104.13-M8 

2. History of the Development of Heat Exchangers for 
I^ow-Prcssure Mobile Oxygen Units, Walter E. Lobo, 
M. W. Kellogg Company, Oct. 4, 1943. 

Div. 11-104.13-M5 

3. History of the Development of Heat Exchangers for 

Loio-Pressurc Mobile Oxygen Units, Walter E. Lobo 
and George T. Skaperdas, M. W. Kellogg Company, 
Oct. 9, 1943. Div. 11-104.13-M6 

4. Liquid Air Fractionation, Progress Report to May 15, 
1944, Walter E. Lobo and B. Williams, OSRD 3768, 
M. W. Kellogg Company, June 13, 1944. 

Div. 11-103.4-M5 

5. Heat Transfer and Pressure Drop in Collins Exchanger, 
Report to Aug. 15, 1944, P. R. Trumpler, OSRD 4143, 
M. W. Kellogg Company, Sept. 19, 1944. 

Div. 11-104.13-M7 

6. Oxygen Plant Development, Report to February 28, 1945, 

V alter E. Lobo, OSRD 4555, M. W. Kellogg Company, 
Feb. 28, 1945. Div. 11-102-M4 

7. Preliminary Results of Tests on Regenerators, Harding 
Bliss, Yale University, Aug. 1, 1942. 

Div. 11-104.13-M2 

8. Regenerators, Progress Report Covering Period from 
August 1, 1942 to March 15, 1943, Harding Bliss, OSRD 
1443, Yale University, May 21, 1943. Div. 11-104.13-M4 

9. Experimental Study of Special Equipment for Use in 

Lozu Temperature Cycles for the Production of Liquid 
and Gaseous Oxygen, Report to July 1, 1945, Harding 
Bliss and Barnett F. Dodge, OSRD 6302, Yale Univer¬ 
sity, Nov. 7, 1945. Div. 11-103.4-M7 

10. A Light-Weight, Automatic, Mechanical Oxygen Gen¬ 

erator, S. C. Collins and Howard O. McMahon, OSRD 
3800, NDCrc-182, Service Projects AC-12, NS-116, 
CE-29, MIT, June 19, 1944. Div. 11-102.111-M7 

11. Oxygen Generating Equipment, Report to June 30, 1945, 
Frederick G. Keyes, OSRD 5329, MIT, July 17, 1945. 

Div. 11-102-M5 



BIBLIOGRAPHY 


403 


12. Report of Heat Transfer and Design of Refrigeration 
Evaporators for the NDRC, W. F. Giauque, Mar. 1, 

1942. 

13. Lozv Temperature Heat Interchangers, W. F. Giauque, 
University of California, Apr. 19, 1943. 

Div. 11-104.13-M3 

14. Liquid Oxygen Trailer Unit, Report to July 25, 1944, 

W. F. Giauque, OSRD 4141, NDCrc-198, University of 
California, Sept. 19, 1944. Div. 11-103.1-M7 

15. Final Report of Central Engineering Laboratory, for 
Period March 1943 through June 1945, John A. Goff 
and Roy W. Banwell, OSRD 5482, OEMsr-934, Univer¬ 
sity of Pennsylvania, June 30, 1945. Div. 11-101-M9 

16. Oxygen Processes, Report to September 1, 1945, OSRD 

5982, NDCrc-206, Air Reduction Company, Inc., Oct. 1, 
1945. Div. 11-103.3-M8 

17. Shipboard Liquid Oxygen Units, Report to February 3, 
1944, T. L. Wheeler and Allen Latham, Jr., OSRD 3369, 
Arthur D. Little Inc., Apr. 6, 1944. Div. 11-103.3-M6 

18. Tests of Performance of Portable Unit Columns for 

Air Rectification, Final Report to January 6, 1944, J. G. 
Aston, OSRD 3699, Pennsylvania State College, May 
29,1944. Div. 11-104.12-M4 

SUPPLEMENTARY 

1. Progress Report, Semi-Portable Oxygen Unit, M-6 Ex¬ 
pander and Unit, November 15 to December 31, 1943, 
W. Dennis. 

2. Monthly Progress Report 1943 to January 31, 1944, J. H. 
Rushton. 

3. Comparison of M-2 and MIT Oxygen Producing Units, 
M. W. Kellogg Company, George T. Skaperdas, Oct. 5, 

1942. 

4. Mobile Oxygen Units Liquid Air Fractionation Sys¬ 
tems, Walter E. Lobo, M. W. Kellogg Company, Feb. 3, 

1943. Div. 11-103.4-M3 

5. Heat Transfer Rates in Collins Exchanger Packings, 
July 24, 1943. 

6. Low-Pressure Mobile Gaseous Oxygen Units Developed 
for NDRC at Olean, N.Y., Clark Bros. Co. Inc. and 
M. W. Kellogg Company, Oct. 29, 1943. 

Div. 11-102.12-M4 

7. Report Summarizing the Work on the M-2R Unit at 
O’Fallon from M. W. Kellogg Company, J. Broadbent, 
Nov. 1, 1943. 

8. Observation of Air Reduction in NDRC Skid Unit on 
December 6, 1943, George T. Skaperdas, December 1943. 

Div. 11-102.12-M6 

9. Visit to Air Reduction Sales Company, December 15 
and 16, 1943, George T. Skaperdas, December 1943. 

Div. 11-102.1-M6 

10. Special Report No. 2, Heat Inter changers for Gases, 

S. C. Collins, Mar. 9, 1942. Div. 11-104.13-MI 

11. Special Report No. 3, Alternating Flozv Scrubber-Heat 

Exchanger, S. C. Collins. Div. 11-104.13-M1 

12. Special Report No. 4, Compressors, Expansion Engine, 
Interchangers, Rectifiers, Frederick G. Keyes, Apr. 15, 
1942. 


Chapter 8 

1. Liquid Air Fractionation, Progress Report to May 15, 

1944, Walter E. Lobo and B. Williams, OSRD 3768, 
M. W. Kellogg Company, June 13, 1944. 

Div. 11-103.4-M5 

2. 7 cchnical Data with Respect to the Properties of Air, 

W alter E. Lobo, OSRD 4206, M. W. Kellogg Company, 
Oct. 6, 1944. Div. 11-102.15-M2 

3. Oxygen Plant Development, Report to February 28, 

1945, Walter E. Lobo, OSRD 4555, M. W. Kellogg 

Company, Feb. 28, 1945. Div. 11-102-M4 

4. A Light-Weight, Automatic, Mechanical Oxygen Gen¬ 
erator to May 31, 1944, S. C. Collins and Howard O. 
McMahon, OSRD 3800, NDCrc-182, Service Projects 
AC-12, NS-116, CE-29, MIT, June 19, 1944. 

Div. 11-102.111-M7 

5. Oxygen Generating Equipment, Report to June 30, 1945, 

Frederick G. Keyes, OSRD 5329, NDCrc-182, MIT, 
July 17, 1945. Div. 11-102-M5 

6. Resume of Oxygen Program, Section 11.1, NDRC, 
Jan. 12, 1944. 

7. Final Report, Liquid Oxygen Trailer Unit, Report to 
July 25, 1944, W. F. Giauque, OSRD 4141, NDCrc-198, 
University of California, Sept. 19, 1944. 

Div. 11-103.1-M7 

8. The Truck Unit for Air Rectification Designed and 
Being Built by W. F. Giauque at the University of 
California, University of California, Feb. 8, 1943. 

Div. 11-103.4-M8 

9. Tray Calculations Made at the Pennsylvania State Col¬ 

lege, J. G. Aston and June Pfister, Pennsylvania State 
College, Feb. 15, 1943. Div. 11-104.11-M3 

10. Heats of Vaporization 0.,-N o , J. G. Aston, S. C. Schu¬ 
mann, and others, OSRD 1507, M. W. Kellogg Com¬ 
pany, June 10, 1943. 

11. Tests of Performance of Portable Unit Columns for 

Air Rectification, Final Report to January 6, 1944, J. G. 
Aston, OSRD 3699, Pennsylvania State College, May 29, 
1944. Div. 11-104.12-M4 

12. Calculation of the Number of Plates in an Air Rectifica¬ 
tion Tower, Report to January 25, 1944, J. G. Aston, 
OSRD 3524, Pennsylvania State College, Apr. 25, 1944. 

Div. 11-104.11-M4 

13. Vapor-Liquid Equilibrium for the System Oxygcn-Nitro- 

gen-Argon, J. G. Aston, OSRD 4493, Contracts OEMsr- 
685 and OEMsr 934, Pennsylvania State College, Dec. 
7, 1944. Div. 11-103.4-M6 

14. Rectification of Air in a Two-Inch Packed Column, 
Barnett F. Dodge, Report No. 365 to August 6, 1942, 
OSRD 876, Yale University, Sept. 17, 1942. 

Div. 11-104.11-M2 

15. Experimental Study of Special Equipment for Use in 

Lozv Temperature Cycles for the Production of Liquid 
and Gaseous Oxygen, Report to July 1, 1945, Harding 
Bliss and Barnett F. Dodge, OSRD 6302, Yale Univer¬ 
sity, Nov. 7, 1945. Div. 11-103.4-M7 



404 


BIBLIOGRAPHY 


16. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for May 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
3861, University of Pennsylvania, July 7, 1944. 

Div. 11-101-M7 

17. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for June 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
3972, University of Pennsylvania, Aug. 2, 1944. 

Div. 11-101-M7 

18. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for August 1 to 31, 
1944, J. H. Rushton, Barnett F. Dodge, and W. L. 
McCabe, OSRD 4207, University of Pennsylvania, Oct. 
6, 1944. Div. 11-101-M7 

19. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for September 1 to 30, 
1944, J. H. Rushton, Barnett F. Dodge, and W. L. 
McCabe, OSRD 4302, University of Pennsylvania, Nov. 
6, 1944. Div. 11-101-M7 

20. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for October 1 to Oc¬ 
tober 31, 1944, J. H. Rushton, Barnett F. Dodge, and 
W. L. McCabe, OSRD 4452, University of Pennsylvania, 
Dec. 13, 1944. Div. 11-101-M7 

21. Final Report of Central Engineering Laboratory, Uni¬ 
versity of Pennsylvania for the Period March 1943 
through June 1945, John A. Goff and Roy W. Banwell, 
OSRD 5482, University of Pennsylvania, June 30, 1945. 

Div. 11-101-M9 

22. Report of All Work Done up to June 1, 1942 Tozvard 
the Development of: (a) Large Shipboard Oxygen 
Liquid Unit 4000 Lb/Hr; (B) Small Portable Gas Unit 
300 Cu Ft/Hr, Wolcott Dennis. 

23. Tests on Oxygen Rectification Equipment Report No. 

206 to February 12, 1942, S. S. Prentiss, OSRD 450, 
Feb. 12, 1942. Div. 11-104.1-MI 

24. Oxygen Processes, Report to Sept. 1, 1945, NDCrc-206, 
OSRD 5928, Air Reduction Company, Inc., Oct. 1. 1945. 

Div. 11-103.3-M8 

SUPPLEMENTARY 

1. Conference on Small Oxygen Units, C. C. Furnas, M. W. 
Kellogg Company, July 13, 1942. Div. 11-102.11-MI 

2. Comparison of M-2 and MIT Oxygen Producing Units, 
M. W. Kellogg Company, G. T. Skaperdas, Oct. 5,, 1942. 

3. Mobile Oxygen Units: Liquid Air Fractionation Sys¬ 

tems, Walter E. Lobo, M. W. Kellogg Company, Feb. 3, 
1943. Div. 11-103.4-M3 

4. Oxygen Project, NDCrc-182: Rectifiers, Special Report 
No. 1, Frederick G. Keyes, MIT, Feb. 27, 1942. 

Div. 11-104.1-M2 

5. Special Report No. 12, Oxygen Producer, Designed and 
Built by S. C. Collins, Frederick G. Keyes, Sept. 25, 
1942. 

6. Letter to Walter E. Lobo from J. G. Ashton dated Janu¬ 
ary 4, 1942 on data on the Stedman packing. 

7. Monthly Report for Period Ending June 30, 1942, J. G. 
Aston. 


8. Progress Report for Month Ending July 31, 1942, J. G. 
Aston. 

9. Monthly Report for August 1942, J. G. Aston. 

10. Monthly Report for September 1942, J. G. Aston. 

11. Monthly Report for October 1942, J. G. Aston. 

12. Monthly Report for November 1942, J. G. Aston. 

13. Monthly Report for December 1942, J. G. Aston. 

14. Progress Report for January and February 1943, J. G. 
Aston. 

15. Monthly Report for March 1943, J. G. Aston. 

16. Monthly Report for April 1943, J. G. Aston. 

17. Monthly Report for May 1943, J. G. Aston. 

18. Monthly Report for June 1943, J. G. Aston. 

19. Monthly Report for July 1943, J. G. Aston. 

20. Monthly Report for August 1943, J. G. Aston. 

21. Monthly Report for September 1943, J. G. Aston. 

22. Tentative Outline of Program of Experimental Investi¬ 
gations for NDRC and Present Status of This Work, 
Barnett F. Dodge, Mar. 18, 1942. 

23. Review of Program of Experimental Work for NDRC, 

Yale University, Sept. 8, 1942. Div. 11-104-MI 

24. Sherwood, Shepley & Holloway, Ind. Eng. Client., 30, 
1938, p. 765. 

Chapter 9 

1. The Investigations Carried Out under Contract No. 

OEMsr-355 with Yale University, Barnett F. Dodge, 
Yale University, June 15, 1942. Div. 11-101-M3 

2. The Investigations Carried Out under Contract No. 

OEM sr-355 with Yale University, Barnett F. Dodge, 
Yale University, Aug. 15, 1942. Div. 11-101-M3 

3. Revici c' of Program of Experimental Work for NDRC, 
Barnett F. Dodge, Yale University, Sept. 8, 1942. 

Div. 11-104-MI 

4. The Investigations Carried Out under Contract No. 

OEMsr-355 with Yale University, Barnett F. Dodge, 
Yale University, Sept. 15, 1942. Div. 11-101-M3 

5. The Investigations Carried Out under Contract No. 

OEMsr-355 with Yale University, Barnett F. Dodge, 
Yale University, Oct. 15, 1942. Div. 11-101-M3 

6. The Investigations Carried Out under Contract No. 

OEMsr-355 with Yale University, Barnett F. Dodge, 
Yale University, Nov. 15, 1942. Div. 11-101-M3 

7. The Investigations Carried Out under Contract No. 

OEMsr-355 with Yale University, Barnett F. Dodge, 
Yale University, Dec. 15, 1942. Div. 11-101-M3 

8. A Colorimetric Method for the Determination of Traces 

of Carbon Dioxide in Air, Progress Report to February 
8, 1943, Norman A. Spector, OSRD 1426, Yale Univer¬ 
sity, May 17, 1943. Div. 11-105.22-MI 

9. The Investigations Carried Out under Contract No. 

OEMsr-355 with Yale University, Barnett F. Dodge, 
Yale University, Feb. 15, 1943. Div. 11 -101 -M3 

10. The Investigations Carried Out under Contract No. 

OEMsr-355 with Yale University, Barnett F. Dodge, 



BIBLIOGRAPHY 


405 


Yale University, Mar. 15, 1943. Div. 11-101-M3 

11. The Investigations Carried Out tinder Contract No. 

OEMsr-355 with Yale University, Barnett F. Dodge, 
Yale University, Apr. 15, 1943. Div. 11-101-M3 

12. The Investigations Carried Out under Contract No. 

OEMsr-355 with Yale University, Barnett F. Dodge, 
Yale University, May 15, 1943. Div. 11-101-M3 

13. The Investigations Carried Out under Contract No. 

OEMsr-355 with Yale University, Barnett F. Dodge, 
Yale University, June 15, 1943. Div. 11-101-M3 

14. The Removal of Carbon Dioxide from Atmospheric Air, 
Progress Report to November 1, 1944, Norman A. Spec- 
tor, OSRD 4340, Yale University, Nov. 14, 1944. 

Div. 11-105.22-M4 

15. Experimental Study of Special Equipment for Use in 

Low Temperature Cycles for the Production of Liquid 
and Gaseous Oxygen, Report to July 1, 1945, Harding 
Bliss and Barnett F. Dodge, OSRD 6302, Yale Univer¬ 
sity, Nov. 7, 1945. Div. 11-103.4-M7 

16. Drying Air with Activated Granular Adsorbents, J. F. 
Skelly, M. W. Kellogg Company, April 3, 1943. 

Div. 11-105.21-MI 

17. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for February 1944, 
J. H. Rushton, Barnett F. Dodge, and others, OSRD 
3523, University of Pennsylvania, Apr. 25, 1944. 

Div. 11-101-M7 

18. Processes for the Removal of Carbon Dioxide from the 
Atmosphere of a Submarine, Allan P. Colburn and Bar¬ 
nett F. Dodge, University of Pennsylvania, Feb. 20, 

1944. Div. 11-105.22-M3 

19. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for August 1944, J. H. 
Rushton, Barnett F. Dodge, and others, OSRD 4207, 
University of Pennsylvania, Aug. 31, 1944. 

Div. 11-101-M7 

20. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for September 1944, 
J. H. Rushton, Barnett F. Dodge, and others, OSRD 
4302, University of Pennsylvania. Div. 11-101-M7 

21. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for October 1944, 
J. H. Rushton, Barnett F. Dodge, and others, OSRD 
4452, University of Pennsylvania. Div. 11-101-M7 

22. The Removal of Traces of Acetylene and Other Hydro¬ 
carbons from Air, J. G. Aston and T. A. Geissman, 
OSRD 4844, University of Pennsylvania, Mar. 5, 1945. 

Div. 11-105.23-MI 

23. Monthly Progress Report, March 1 to 31, 1945, W. L. 
McCabe, SRD 5040. 

24. Final Report of Central Engineering Laboratory, Uni¬ 
versity of Pennsylvania, for the Period March 1943 
through June 1945, John A. Goff and Roy W. Banwell, 
OSRD 5482, OEMsr-934, Service Project No. NL-B42, 
NA-106, and others, University of Pennsylvania, June 30, 

1945. Div. 11-101-M9 

25. Progress Report, R. N. Pease, OSRD 4898. 


26. Literature Survey on the Estimation of Small Amounts 
of Hydrocarbons in Air: The Importance of These Com¬ 
pounds in the Rectification of Air, William R. James, Jr. 

Div. 11-105.1-M2 

27. Estimation of Oil Contamination in Air from Compres¬ 

sors of Portable Air Rectification Units: Report to Janu¬ 
ary 19, 1944, J. G. Aston, OSRD 3484, Pennsylvania 
State College, Apr. 14, 1944. Div. 11-105.1-MI 

SUPPLEMENTARY 

1. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for 1943 to January 
31, 1944, J. H. Rushton, University of Pennsylvania. 

Div. 11-101-M7 

2. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for March 1944, J. H. 
Rushton and Barnett F. Dodge, OSRD 3652, University 
of Pennsylvania, May 19, 1944. Div. 11-101-M7 

3. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for April 1944, J. H. 
Rushton and W. L. McCabe, OSRD 3760, University of 
Pennsylvania, June 9, 1944. Div. 11-101-M7 

4. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for May 1944, J. H. 
Rushton, W. L. McCabe, and Barnett F. Dodge, OSRD 
3861, University of Pennsylvania, July 7, 1944. 

Div. 11-101-M7 

5. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for June 1944, J. H. 
Rushton, W. L. McCabe, and Barnett F. Dodge, OSRD 
3972, University of Pennsylvania, Aug. 2, 1944. 

Div. 11-101-M7 

6. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for July 1944, J. H. 
Rushton, Barnett F. Dodge, and W. L. McCabe, OSRD 
4142, University of Pennsylvania, Sept. 19, 1944. 

Div. 11-101-M7 

7. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for November 1 to 30, 
1944, J. H. Rushton, W. L. McCabe, and Barnett F. 
Dodge, OSRD 4516, University of Pennsylvania. 

Div. 11-101-M7 

8. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for December 1 to 31, 

1944, J. H. Rushton, W. L. McCabe, and Barnett F. 
Dodge, OSRD 4623, University of Pennsylvania. 

Div. 11-101-M7 

9. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for January 1 to 31, 

1945, J. H. Rushton, W. L. McCabe, and Barnett F. 
Dodge, OSRD 4732, University of Pennsylvania. 

Div. 11-101-M7 

10. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for February 1 to 28, 
1945, J. H. Rushton, W. L. McCabe, and Barnett F. 
Dodge, OSRD 4879, University of Pennsylvania, Mar. 
30, 1945. Div. 11-101-M7 



406 


BIBLIOGRAPHY 


11. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for April 1 to 30, 
1945, W. L. McCabe, OSRD 5153, University of Penn¬ 
sylvania, May 31, 1945. Div. 11-101-M7 

12. The Investigations Carried Out under Contract OEMsr- 

232 and New Contract Symbol 964 until Yale University; 
Monthly Report for March 18, 1942, Barnett F. Dodge, 
Yale University, Apr. 19, 1942. Div. 11-101-M2 

13. The Investigations Carried Out under Contract OEMsr- 

355 until Yale University, Barnett F. Dodge, Yale Uni¬ 
versity, July 15, 1942. Div. 11-101-M3 

14. Oxygen Generating Equipment, Report to June 30, 1945, 
Frederick G. Keyes, OSRD 5329, MIT, July 17, 1945. 

Div. 11-102-M5 

15. Absorption of C0 2 from Normal Air by Soda Lime, 

T. L. Wheeler, Arthur D. Little Company, Inc., Dec. 8, 
1943. Div. 1 1-105.22-M2 

Chapter 10 

1. A Colorimetric Method for the Determination of Traces 

of Carbon Dioxide in Air: Progress Report to Febru¬ 
ary 8, 1943, Norman A. Spector, OSRD 1426, Yale Uni¬ 
versity, May 17, 1943. Div. 11-105.22-MI 

2. Performance of Heat Insulating Materials at Lozv Tem¬ 

peratures, John B. Dwyer, Yale University, Nov. 22, 
1943. Div. 11-104.131-M2 

3. Insulating Pozver of Glass Wool, Arthur D. Little Co., 

Apr. 8 ,1943. Div. 11-104.131-MI 

4. History of the Development of Heat Exchangers for 

Lozv-Pressure Mobile Oxygen Units, Walter E. Lobo 
and George T. Skaperdas, M. W. Kellogg Company, 
Oct. 9, 1943. Div. 11-104.13-M6 

5. Oxygen Plant Development Report to February 28, 1945, 

Walter E. Lobo, OSRD 4555, M. W. Kellogg Company, 
Feb. 28, 1945. Div. 11-102-M4 

6. Methods of Production and Calibration of Combination 

Vapor Pressure and Gas Dial Thermometers, Paul Erb- 
guth and J. G. Aston, OSRD 4780, University of Penn¬ 
sylvania, Jan. 26, 1945. Div. 11-104.2-M5 

7. The Removal of Traces of Acetylene and Other Hydro¬ 
carbons from Air, J. G. Aston and T. A. Geissman, Uni¬ 
versity of Pennsylvania, Mar. 5, 1945. 

Div. 11-105.23-MI 

8. Final Report of Central Engineering Laboratory, for 

the Period March 1943 through June 1945, John A. Goff 
and Roy W. Banwell, OSRD 5482, University of Penn¬ 
sylvania, June 30, 1945. Div. 11-101-M9 

9. Combined Oxygen Vapor Pressure and Gas Thermome¬ 
ter: Final Report to January 6,1944, J. G. Aston, OSRD 
3483, Pennsylvania State College, Apr. 14, 1944. 

Div. 11-104.2-M3 

SUPPLEMENTARY 

1. Combined Oxygen Vapor-Pressure and Gas Thermome¬ 
ters for Use in Temperature Range — 320°F to 100°F, 
Donald S. Parker and Malcolm L. Sagenkahn, Pennsyl¬ 
vania State College, Sept. 24, 1943. Div. 11-104.2-MI 


Chapter 11 

1. Progress Report No. 1, Work from October 1, 1940 
to February 15, 1941, Clifford Hach and Harvey Diehl, 
Iowa State College, Feb. 17, 1941. 

2. The Effect of Light on the Dcoxygcnation of Disalicyl- 
atcthylcncdiimine Cobalt, Progress Report No. II; 
Work from February 15 to March 15, 1941, Clifford 
Hach and Harvey Diehl, Iowa State College. 

3. Progress Report No. Ill, Work from March 15, 1941 
to Aug. 25, 1941, Harvey Diehl, Clifford Hach, and G. 
Harrison, Iowa State College. 

4. Progress Report No. V, Work Done from November 
10, 1941 to January 5, 1942, Harvey Diehl, Clifford 
Hach, and G. Harrison, Iowa State College, Jan. 8, 
1942. 

5. Chelate Compounds for Oxygen Production and Stor¬ 

age, Melvin Calvin, University of California, Mar. 11, 
1942 Div. 11-102.211-M6 

6. Monthly Progress Report, April 15 to May 15, 1942, 

Melvin Calvin, University of California. 

7. Chelate Oxygen Compounds: Monthly Progress Report 

Covering Period from May 15 to June 15, 1942, Melvin 
Calvin, W. K. Wilmarth, and others, University of 

California. Div. 11-102.211-M9 

8. Chelate Oxygen Compounds and Equipment for Their 
Use, Report No. 378 to August 1, 1942, Melvin Calvin, 
OSRD 921, University of California, Sept. 30, 1942. 

Div. 11-102.211-M10 

9. Chelate Oxygen Compounds and the Mechanism of the 

Absorption Reaction: Report No. 398 to September 1, 
1942, Melvin Calvin, OSRD 1018, University of Cali¬ 
fornia, Oct. 21, 1942. Div. 11-102.211-M12 

10. Chelate Oxygen Compounds: Monthly Progress Report 

Covering Period from September 1 to October 1, 1942, 
Melvin Calvin, W. K. Wilmarth, and others, Univer¬ 
sity of California. Div. 11-102.211-M9 

11. Chelate Oxygen Compounds: Monthly Progress Report 

Covering Period from October 1 to September 1, 1942, 
Melvin Calvin, W. K. Wilmarth, and others, University 
of California. Div. 11-102.211-M9 

12. Chelate Oxygen Compounds: Monthly Progress Report 

Covering Period from December 1 to February 1, 1943, 
Melvin Calvin, W. K. Wilmarth, and others, University 
of California. Div. 11-102.211-M9 

13. Chelate Oxygen Compounds: Monthly Progress Report 

Covering Period from April 1 to June 1, 1943, Melvin 
Calvin, W. K. Wilmarth, and others, University of 
California. Div. 11-102.211-M9 

14. The Actiz’itics of the Rumford Research Laboratory in 

Connection with the Development and Production of 
Salcomine, Report Covering Period from December 5, 
1941 to July 1, 1942, Karl A. Holst, Rumford Chemical 
Works, July 6, 1942. Div. 11-102.212-M5 

15. The Progress of the Research on Salcomine and Re¬ 
lated Compounds During November 1942, Karl A. Holst, 
Rumford Chemical Company, Dec. 11, 1942. 

Div. 11-102.211-M13 




BIBLIOGRAPHY 


407 


16. The Preparation of 75 Lbs. of 3-Fluoro-SalicyIaldehyde 

and 20 Lbs. of the Active Cobalt Chelate, Melvin Calvin, 
L. Ferguson, and others, University of California, Apr. 
10, 1944. Div. 11-102.211-M37 

17. Process for Producing o-Ethavan, Final Report, O. J. 
Weinkauff and L. P. Kyrides, Monsanto Chemical Com¬ 
pany, July 9, 1943. 

18. Tentative Process for o-Ethavan, L. P. Kyrides, H. 

Anthes, and others, Monsanto Chemical Company, 
Sept. 21, 1943. Div. 11-102.211-M27 

19. Chelate Oxygen Compounds: Monthly Progress Report 

Covering Period from February 1 to April 1, 1943, 
Melvin Calvin, W. K. Wilmarth, and others, Univer¬ 
sity of California. Div. 11-102.211-M9 

20. Chelate Oxygen Compounds: Monthly Progress Report 

Covering Period from November 1 to December 1, 1942, 
Melvin Calvin, W. K. Wilmarth, and others. Univer¬ 
sity of California. Div. 11-102.211-M9 

21. Report, Sc.D. Thesis, R. L. von Berg, Massachusetts 
Institute of Technology, April 1944. 

22. The Crystal Structure of the Cobalt Chelates and the 

Mechanism of the Oxygenation Process, E. W. Hughes, 
C. H. Baukelew, and Melvin Calvin, University of 
California, Mar. 15, 1944. Div. 11-102.211-M34 

23. Properties of Salcomine and Ethominc and the Separa¬ 
tion of Atmospheric Oxygen Therewith, A. M. Smith 
and W. E. Catterall, OSRD 1539, Massachusetts Insti¬ 
tute of Technology, June 25, 1943. 

Div. 11-102.211-M24 

24. The Development, Properties, and Use of Chelate Com¬ 
pounds for the Production of Oxygen: Report to Au¬ 
gust 31, 1944, Melvin Calvin, OSRD 4161, University 
of California, Sept. 23, 1944. Div. 11-102.211-M41 

25. Catalogue of X-Ray Powder Diagrams of a Number of 

Pertinent Cobalt Chelate Compounds, E. W. Hughes 
and Melvin Calvin, University of California, Apr. 28, 
1944. Div. 11-102.211-M38 

26. Preparation of Intermediates for Oxygen-Carrying Che¬ 
late Complexes: Report to March 1, 1945, T. A. Geiss- 
man, William G. Young, and others, OSRD 4845, 
University of California at Los Angeles, Mar. 23, 1945. 

Div. 11-102.211-M42 

27. Investigation of Oxygen Supply: Progress Report to 
November 1, 1941, E. R. Gilliland, OSRD 291, Massa¬ 
chusetts Institute of Technology, Dec. 8, 1941. 

Div. 11-102.2-MI 

28. Investigation of Oxygen Supply: Report Covering Pe¬ 
riod to May 31, 1942, E. R. Gilliland, OSRD 613, Mas¬ 
sachusetts Institute of Technology, June 8, 1942. 

Div. 11-102.212-M3 

29. The Regenerative Chemical System for Oxygen Pro¬ 
duction on Board Aircraft: Report to July 1, 1943, J. P. 
Longwell and W.E. Catterall, OSRD 1620, Massachu¬ 
setts Institute of Technology, July 19, 1943. 

Div. 11-102.21-M6 

30. Special Engineering Systems Utilizing Chelate Chemi¬ 
cal Absorbents for Oxygen Production: Report to July 
1, 1943, Charles R. Hetherington and W. E. Catterall, 


OSRD 1579, Massachusetts Institute of Technology, 
July 9, 1943. Div. 11-102.211-M5 

31. Salcomine Deterioration, C. D. Bell and E. Field, E. I. 
du Pont de Nemours & Co., Inc., Sept. 30, 1942. 

Div. 11-102.212-M7 

32. Process Development Work on Salcomine Suspension 
for Month of September 1942, L. Squires, E. I. du Pont 
de Nemours & Co., Oct. 14, 1944. 

33. Study of Salcomine Deterioration, E. Field and D. M. 
Smith, E. I. du Pont de Nemours & Co., October 1 to 
December 12, 1942. 

34. The Preparation and Properties of Mixed Aldehyde 

Cobalt Derivatives, Karl A. Holst, Rumford Chemical 
Co., Jan. 16, 1943. Div. 11-102.211-Mil 

35. Development of a Test Unit for Production of Oxygen 

by a Regenerative Chemical, Supplement Nos. 2, 4, 5, 
6 and 7, Progress Reports Covering Period from Au¬ 
gust 15, 1943 to March 15, 1945, T. L. Wheeler and Ben¬ 
jamin Fogler, OSRD 3359, Arthur D. Little, Inc., Mar. 
7, 1944. Div. 11-102.213-M4 

36. Toxicity Tests on Salcomine and Salcomine Powders, 
Julius M. Coon, Howard Glass, and Clarence E. Lush- 
baugh, OSRD 892, University of Chicago Toxicity 
Laboratory, Sept. 22, 1942. 

37. Toxicity of Chemical Warfare Agents, Informal 
Monthly Progress Report, University of Chicago Tox¬ 
icity Laboratory, Oct. 10, 1944. 

38. The Effect of Salcomine on Workmen, with Summaries 
of Physical Examinations, Arthur D. Little, Inc., Feb. 1, 

1944. Div. 11-102.211-M31 

39. The Salcomine Poisoning of T. A. Geissman, Roy W. 
Banwell, University of Pennsylvania, January 1944. 

Div. 11-102.212-M16 

40. “Chelate Compounds,” T. Tsumabi, Bulletin of the 
Chemical Society of Japan, 13, 1938, pp. 252-260. 

Div. 11-102.211-MI 

41. Oxygen Plant Development Employing Regenerative 
Chemicals. Report to March 16, 1945, Walter E. Lobo 
and C. Bockius, OSRD 5154, M. W. Kellogg Company 
and American Machine Defense Corporation, May 31, 

1945. Div. 11-102.213-M5 

42. Oxygen-Carrying Metallic Complexes of the Salcomine 
Type, T. A. Geissman, OSRD 5927, University of 
Pennsylvania, June 30, 1945. Div. 11-102.212-M17 

43. The Design of Circulating-Solid Apparatus for the Re¬ 
covery of Oxygen from the Atmosphere Using the Oxy¬ 
gen Carrier Co-Ox M, Clifford Hach and Harvey 
Diehl, Iowa State College, Report L No. 1 to the NRL 
and No. 46 to NDRC covering period May 20, 1942 to 
October 31, 1942. 

44. Oxygen Generating Unit, from Commanding Officer 
of USS Prairie to Chief, BuShips, O. A. Kneeland, 
Feb. 15, 1944. 

45. Operating and Maintenance Instructions for Clark 2- 
Stage 5 "x3"x3^" Dri-Oxygen Compressor, Clark 
Bros. Company. 



408 


BIBLIOGRAPHY 


46. Instructions for Operation and Maintenance of NDRC 

Regenerative Oxygen Unit, Arthur D. Little, Inc., Oct. 
1, 1943. Div. 11-102.21-M7 

47. Installation and Trial Test Run of the NDRC Rcgener- 
ative Oxygen Unit Aboard the U.S.S. Prairie, C. J. 
Matthew, A. D. Little, Inc., Oct. 29, 1943. 

48. Production of Oxygen by Regenerative Chemicals, W. 

W. Beck, Aug. 19, 1942. Div. 11-102.21-M3 

49. General Description Salcomine Oxygen Navy Unit, 
Type C-4, M. W. Kellogg Co., Apr. 20, 1942. 

50. Small Oxygen Plants (Salcomine Process) for Ship¬ 
board Installation, M. W. Kellogg Co., Jan. 19, 1943. 

51. Characteristics of the Oxygen Absorbents Ethomine 
and Fluorine, Robert L, von Berg and W. E. Catterall, 
OSRD 5407, June 30, 1945. 

52. Production of Salcomine and Related Compounds: Re¬ 
port to September 4, 1945, Karl A. Holst, OSRD 6052, 
Rumford Chemical Works, Oct. 1, 1945. 

Div. 11-102.211-M44 

53. Preparation of Intermediates for Oxygen-Carrying Che¬ 
late Complexes: Report to March 1, 1945, T. A. Geiss- 
man, William G. Young, and others, OSRD 4845, Uni¬ 
versity of California at Los Angeles, Mar. 23, 1945. 

Div. 11-101.211-M42 

54. Preparation of Disalicylaltetrafluoroethylenediamine: 

Monthly Progress Report Covering Period from July 1 
to Aug. 4, 1944, Frederick S. Bacon, University of 
Pennsylvania, Aug. 7, 1944. Div. 11-102.211-M40 

55. Monthly Progress Report Covering Period June 1 to 
June 30, 1944: Preparation of Disalicylaltctrafluoro- 
ethylenediamine, Frederick S. Bacon, July 1, 1944. 

SUPPLEMENTARY 

56. Report for August 1942, W. S. Gleeson, American Ma¬ 
chine Defense Corp., Sept. 8, 1942. 

57. Kellogg Compressor Project #SSRC-20, J. D. Wells, 
American Machine Defense Corp., Oct. 9, 1942. 

58. Progress Report for September 1942, F. H. Wells, 
American Machine Defense Corp., Oct. 9, 1942. 

59. Progress Report for October 1942, F. H. Wells, Ameri¬ 
can Machine Defense Corp., Nov. 6, 1942. 

60. Progress Report for November 1942, F. H. Wells, 
American Machine Defense Corp., Dec. 10, 1942. 

61. Progress Report for December 1942, F. H. Wells, 
American Machine Defense Corp., Jan. 5, 1943. 

62. Progress Report for January 1943, F. H. Wells, Ameri¬ 
can Machine Defense Corporation, Feb. 11, 1943. 

63. Progress Report for February 1943, J. R. Vickery, 
American Machine Defense Corp., Mar. 8, 1943. 

64. Progress Report, C-2 Salcomine Unit at the Whitlock 
Mfg. Co., for March 1943, J. R. Vickery, American 
Machine Defense Corp., Apr. 5, 1943. 

65. Salcomine Report for Month of June 1942, E. P. Bart¬ 

lett, A. G. Weber, and others, E. I. duPont de Nemours 
& Co., Inc. Div. 11-102.212-M2 

66. Oil-Suspension Salcomine Process as Developed by the 
Ammonia Department of the duPont Company, M. W. 


Kellogg Co., Aug. 5, 1942. Div. 11-102.212-M6 

67. Salcomine Report for Month of July 1942, E. P. Bart¬ 

lett, A. G. Weber, and others, E. I. duPont de Nemours 
& Co., Inc., Aug. 13, 1942. Div. 11-102.212-M2 

68. Process Development Work on Salcomine Suspension, 
L. Squires, E. I. duPont de Nemours & Co., Sept. 17, 
1942. 

69. Manganese Absorbents in the Production of Oxygen 

from Air, E. I. duPont de Nemours & Co., Inc., De¬ 
cember 1942. Div. 11-102.211-M14 

70. Informed Report on the Progress of the Research on 
Salcomine and Related Compounds, Dec. 12, 1942 to 
Feb. 12, 1943, E. Field and D. M. Smith, E. I. duPont 
de Nemours & Co. 

71. Informed Report on the Progress of the Research on 
Salcomine and Related Compounds, Feb. 12, 1943 to 
Mar. 12, 1943, D. M. Smith, E. I. duPont de Nemours 
& Co. 

72. Report on Salcomine, E. Field, C. D. Bell, J. V. E. 
Hardy, OSRD 1616, E. I. duPont de Nemours & Co., 
June 3, 1943. 

73. Salcomine as an Absorbent for Separating Atmospheric 

Oxygen, E. Field, C. D. Bell, and J. V. E. Hardy, 
OSRD 1616, E. I. duPont de Nemours & Co., Inc., 
July 16, 1943. Div. 11-102.212-M13 

74. Analysis and Degradation Study of Salcomine (Final 
Report to October 1, 1943), OSRD 1951, E. I. duPont 
de Nemours & Co., Inc., Oct. 25, 1943. 

Div. 11-102.212-M15 

75. Report IV, August 25, 1941 to November 10, 1941, Har¬ 

vey Diehl, Clifford Hach, and G. Harrison, Iowa State 
College. Div. 11-102.211-M2 

76. Report VI, December 15, 1941 to January 2, 1942, Clif¬ 

ford Hach, Harvey Diehl, and others, Iowa State Col¬ 
lege. Div. 11-102.211-M2 

77. Monthly Progress Report, Harvey Diehl, Iowa State 
University, Feb. 14, 1942. 

78. Report XII, February 14, 1942 to March 14, 1942, Clif¬ 

ford Hach, Harvey Diehl, and others, Iowa State Col¬ 
lege, Mar. 14, 1942. Div. 11-102.211-M2 

79. Development of 0 o -Carrying Chemicals, Report XXVI, 

December 1, 1941 to March 15, 1942, Harvey Diehl and 
others, OSRD 574, Iowa State College. 

80. Report XXIII, March 14, 1942 to April 15, 1942, Clif¬ 

ford Hach, Harvey Diehl, and others, Iowa State 
College, Apr. 16, 1942. Div. 11-102.211-M2 

81. Report XVII, February 14, 1942 to March 31, 1942, 

Clifford Hach, Harvey Diehl, and others, Iowa State 
College, Apr. 27, 1942. Div. 11-102.211-M2 

82. Report XXI, February 20, 1942 to March 2, 1942, Clif¬ 

ford Hach, Harvey Diehl, and others, Iowa State Col¬ 
lege, May 6, 1942. Div. 11-102.211-M2 

83. Report XXVII, March 26, 1942 to May 13, 1942, Clif¬ 

ford Hach, Harvey Diehl, and others, Iowa State Col¬ 
lege, May 13, 1942. Div. 11-102.211-M2 

84. Report XXVIII, April 15, 1942 to May 13, 1942, Clif¬ 

ford Hach, Harvey Diehl, and others, Iowa State Col¬ 
lege, May 13, 1942. Div. 11-102.211-M2 





BIBLIOGRAPHY 


409 


85. Report XXXIII, May 13, 1942 to June 15, 1942, Clif¬ 

ford Hach, Harvey Diehl, and others, Iowa State Col¬ 
lege, June 17, 1942. Div. 11-102.211-M2 

86. Report XXXII, April 1, 1942 to May 15, 1942, Clif¬ 

ford Hach, Harvey Diehl, and others, Iowa State 
University, July 14, 1942. * Div. 11-102.211-M2 

87. Report XXIV, January 24, 1942 to April 29, 1942, 
G. Harrison, Iowa State University, July 20, 1942. 

88. Report XXXIX, June 15, 1942 to July 23, 1942, Har¬ 
vey Diehl, Iowa State University, July 23, 1942. 

89. Report XXXVIII, May 13, 1942 to July 24, 1942, 
L. Liggett, J. Head, Harvey Diehl, and Melvin Calvin 
and co-workers, Iowa State University, July 24, 1942. 

90. Report XXXIV, May 20, 1942 to July 23, 1942, Clif¬ 
ford Hach and Harvey Diehl, Iowa State University, 
July 25, 1945. 

91. Report XXXV, June 1, 1942 to July 25, 1942, R. W. 
Schwandt and Harvey Diehl, Iowa State University, 
Aug. 5, 1942. 

92. Report XL, Harvey Diehl, Iowa State University, July 
24, 1942 to August 15, 1942. 

93. Development of Oxygen-Carrying Chemicals, Report 
LX VI, Iowa State University, April 15, 1942 to Sep¬ 
tember 1, 1942. 

94. Development of Oxygen-Carrying Compounds, Report 

XLVI, April 15, 1942 to September 1, 1942, Harvey 
Diehl, OSRD 945, OEMsr-215, Iowa State Univer¬ 
sity, Oct. 16, 1942. Div. 11-102.211-Mil 

95. Report XLV, July 11, 1942 to August 24, 1942, 
L. Liggett and Harvey Diehl, Iowa State Univer¬ 
sity, Sept. 11, 1942. 

96. Report XLIV, May 1, 1942 to June 1, 1942, 
J. Matthews, Jr., and Harvey Diehl, Iowa State 
University, Sept. 14, 1942. 

97. Report LI, August 15, 1942 to September 15, 1942, 
Harvey Diehl, Iowa State University, September 15, 
1942. 

98. Oxygen Problem, Summary of Reports from Octo¬ 

ber 20, 1938 to about September 15, 1942, Clifford 
Hach, Harvey Diehl, Iowa State University; and other 
institutions. Div. 11-102.211-M2 

99. Report XLI, April 24, 1942 to May 20, 1942, J. Head 
and Harvey Diehl, Iowa State University, Sept. 21, 
1942. 

100. Report XXIX, April 17, 1942 to May 15, 1942, J. Head 
and Harvey Diehl, Iowa State University, Sept. 21, 
1942. 

101. Report XLII, July 22, 1942 to August 21, 1942, G. Har¬ 
rison and Harvey Diehl, Iowa State University, Sept. 
22, 1942. 

102. Report XXXI, March 15, 1942 to September 7, 1942, 
Clifford Hach, L. Liggett, and Harvey Diehl, Iowa 
State University, Sept. 23, 1942. 

103. Report XXXVII, June 16, 1942 to August 31, 1942, 
R. Brouns and Harvey Diehl, Iowa State University, 
Sept. 25, 1942. 

104. Report LII, September 15, 1942 to October 15, 1942, 


Harvey Diehl, Iowa State University. 

105. The Design of a Circulating-Solid Apparatus for the 
Recovery of Oxygen from the Atmosphere Using the 
Oxygen Carrier Co-Ox M, May 20, 1942 to October 
31, 1942, Clifford Hach and Harvey Diehl, Iowa State 
University. 

106. Report XLVIII, August 19, 1942 to November 4, 1942, 
G. Harrison and Harvey Diehl, Iowa State University, 
Nov. 4, 1942. 

107. Report LVI, October 15, 1942 to November 16, 1942, 
Harvey Diehl, Iowa State University. 

108. Report LV, October 5, 1942 to November 18, 1942, 
J. Read and Harvey Diehl, Iowa State University, 
Dec. 3, 1942. 

109. Report LVIII, November 16, 1942 to December 15, 
1942, Harvey Diehl, Iowa State University. 

110. Oxygen Problem, Report LVII, Clifford Hach, Ross 

Curtis, and Harvey Diehl, Iowa State University, Dec. 
15, 1942. Div. 11-102.111-M4 

111. Report LIX, October 21, 1942 to November 14, 1942, 
L. Liggett and Harvey Diehl, Iowa State University, 
Jan. 15, 1943. 

112. Report LX, November 14, 1942 to January 1, 1943, 
L. Liggett and Harvey Diehl, Iowa State University, 
Jan. 15, 1943. 

113. Report LI, September 1, 1942 to December 18, 1942, 
R. Brouns and Harvey Diehl, Iowa State University, 
Jan. 20, 1943. 

114. Report LIII, October 26, 1942 to October 29, 1942, 
R. Curtis and Harvey Diehl, Iowa State University, 
Jan. 26, 1943. 

115. Report LXIII, November 19, 1942 to December 29, 
1942, J. Read and Harvey Diehl, Iowa State Univer¬ 
sity, Feb. 5, 1943. 

116. Apparatus for the Determination of the Rate of Oxy¬ 
genation, Report LXI, G. Harrison, R. Brouns, and 
Harvey Diehl, Iowa State University, Feb. 16, 1943. 

Div. 11-102.21-M4 

117. Report LXV, December 15, 1942 to February 15, 1943, 
Harvey Diehl, Iowa State University, Feb. 16, 1943. 

118. Report LIV, October 21, 1942 to December 15, 1942, 
G. Harrison and Harvey Diehl, Iowa State Univer¬ 
sity, Feb. 17, 1943. 

119. Report LXI1, December 18, 1942 to February 15, 1943, 
R. Brouns and Harvey Diehl, Iowa State University, 
Feb. 19, 1943. 

120. Report LXIV, December 20, 1942 to February 27, 1943, 
J. Head and Harvey Diehl, Iowa State University, 
Mar. 4, 1943. 

121. Report XLVII, Work Intermittently from March 22, 
1942 to March 8, 1943, J. Head and Harvey Diehl, 
Iowa State University, Mar. 11, 1943. 

122. Report LXIX, February 16, 1943 to March 15, 1943, 
Harvey Diehl, Iowa State University, Mar. 15, 1943. 

123. Report LXVI, February 15, 1943 to March 1, 1943, 
R. Brouns and Harvey Diehl, Iowa State University, 
Mar. 30, 1943. 



410 


BIBLIOGRAPHY 


124. Report LXXIV, March 16, 1943 to April 15, 1943, 
Harvey Diehl, Iowa State University, Apr. 1, 1943. 

125. Development of Oxygen-Carrying Chemicals, (Part 
111, Progress Report Covering Period from Septem¬ 
ber 1, 1942 to April 20, 1943), Harvey Diehl, OSRD 
1448, Iowa State University, May 24, 1943. 

Div. 11-102.211-M23 

126. Report LXX, March 1, 1943 to April 10, 1943, R. Cur¬ 
tis, L. Liggett, and H. Diehl, May 5, 1943. 

127. Report LXXVI, April 15, 1943 to May 14, 1943, 
Harvey Diehl, Iowa State University, May 17, 1943. 

128. Development of Oxygen-Carrying Chemicals, Fourth 
Progress Report No. 73 covering period May 20, 1942 
to May 20, 1943, A Circulating-Solid Apparatus for 
the Manufacture of Oxygen, Clifford Hach and Har¬ 
vey Diehl, Iowa State University, Oct. 13, 1943. 

Div. 11-102.211-M28 

129. Report LXXVII, April 20 to May 5, 1943, L. Liggett, 
J. Mathews, R. Curtis, and Harvey Diehl, Iowa State 
University, May 27, 1943. 

130. Development of Oxygen-Carrying Chemicals, Fifth 
and Final Report No. 79, Covering Period from April 
20, 1943 to June 30, 1943, Harvey Diehl, OSRD 1850, 
Iowa State University, Oct. 13, 1943. 

Div. 11-102.211-M29 

131. Development of Test Unit for Production of Oxygen 
by a Regenerative Chemical, Progress Report for De¬ 
cember 1941, Arthur D. Little, Inc., Feb. 2, 1942. 

Div. 11-102.211-M5 

132. Report on Development of Manufacturing Process for 
Salcomine by Rumford Chemical Works (sub-contrac¬ 
tor to ADL), Frederick S. Bacon, Arthur D. Little, 
Inc., Apr. 27, 1942. 

133. Development of Test Unit for Production of Oxygen 
by a Rengenerative Chemical [Report] for April, Fred¬ 
erick S. Bacon, Arthur D. Little, Inc., May 14, 1942. 

134. Development of Test Unit for Production of Oxygen 
by a Regenerative Chemical [Report] for May, 1942, 
Frederick S. Bacon, Arthur D. Little, Inc., June 12, 1942. 

135. Development of Test Unit for Production of Oxygen 
by a Regenerative Chemical [Report] for June, 1942, 
Frederick S. Bacon, Arthur D. Little, Inc., July 14, 1942. 

136. Development of Test Unit for Production of Oxygen 
by a Regenerative Chemical [Report] for August, 1942, 
Frederick S. Bacon, Arthur D. Little, Inc., Sept. 11, 

1942. 

137. Development of Test Unit for Production of Oxygen 
by a Regenerative Chemical, Progress Report for Jan¬ 
uary and February, 1942, T. L. Wheeler and Benjamin 
Fogler, Arthur D. Little, Inc., Mar. 8, 1943. 

Div. 11-102.211-M15 

138. Absorption Rate Determinations Using Small Sa)nplcs, 
Benjamin Fogler, Arthur D. Little, Inc., Mar. 17, 1943. 

Div. 11-102.211-M18 

139. Development of Test Unit for Production of Oxygen 
by a Regenerative Chemical, Progress Report for March 

1943, T. L. Wheeler and Benjamin Fogler, Arthur D. 

Little, Inc., Apr. 15, 1943. Div. 11-102.211-M15 

140. Development of Test Unit for Production of Oxygen 


by a Regenerative Chemical, Progress Report Covering 
Period from April 1 through May 15, 1943, T. L. 
Wheeler and Benjamin Fogler, Arthur D. Little, Inc., 
May 22, 1943. Div. 11-102.211-M15 

141. Dcz'elopmcnt of Test Unit for Production of Oxygen 

by a Rgcnerative Chemical, Progress Report Covering 
Period May 15, 1943 through June 15, 1943, T. L. 
Wheeler and Benjamin Fogler, Arthur D. Little, Inc., 
June 15, 1943. Div. 11-102.211-M15 

142. Development of Test Unit for Production of Oxygen 

by a Regenerative Chemical, Progress Report Covering 
Period from June 15, 1943 through July 15, 1943, T. L. 
Wheeler and Benjamin Fogler, Arthur D. Little, Inc., 
July 21, 1943. Div. 11-102.211-M15 

143. Development of Test Unit for Production of Oxygen 

by a Regenerative Chemical, Progress Report Covering 
Period front July 15 to August 15, 1943, T. L. Wheeler 

and Benjamin Fogler, Arthur D. Little, Inc., Aug. 19, 

1943. Div. 11-102.211-M15 

144. Development of Test Unit for Production of Oxygen 

by a Regenerative Chemical, Progress Report Covering 
Period from August 15 to September 20, 1943, T. L. 
Wheeler and Benjamin Fogler, Arthur D. Little, Inc., 
Sept. 27, 1943. Div. 11-102.213-M4 

145. Development of Test Unit for Production of Oxygen 

by a Regenerative Chemical, Progress Report Covering 
Period from September 20 through October 10, 1943, 
T. L. Wheeler and Benjamin Fogler, Arthur D. Little, 
Inc., Oct. 20, 1943. Div. 11-102.213-M4 

146. Development of Test Unit for Production of Oxygen 
by a Regenerative Chemical [Report] through May 15, 

1944, T. L. Wheeler and Benjamin Fogler, Arthur D. 

Little, Inc., May 22, 1944. Div. 11-102.213-M4 

147. Development of Test Unit for Production of Oxygen 

by a Regenerative Chemical, Progress Report Covering 
Period from May 15 through June 15, 1944, T. L. 
Wheeler and Benjamin Fogler, Arthur D. Little, Inc., 
June 16, 1944. Div. 11-102.213-M4 

148. Development of Test Unit for Production of Oxygen 

by a Rcgencratrve Chemical, Progress Report Covering 
Period from June 15 through July 15, 1944, T. L. 
Wheeler and Benjamin Fogler, Arthur D. Little, Inc., 
July 20. 1944. Div. 11-102.213-M4 

149. Development of Test Unit for Production of Oxygen 

by a Regenerative Chemical, Progress Report Covering 
Period from July 15 through August 15, 1944, T. H. 
Wheeler and Benjamin Fogler, Arthur D. Little, Inc., 
Aug. 25, 1944. Div. 11-102.213-M4 

150. Development of Test Unit for Production of Oxygen 

by a Regenerative Chemical, Progress Report Covering 
Period from August 15 through September 15, 1944, 
T. H. Wheeler and Benjamin Fogler, Arthur D. Little, 
Inc., Sept. 21, 1944. Div. 11-102.213-M4 

151. Dcz'elopmcnt of Test Unit for Production of Oxygen 

by a Regenerative Chemical, Progress Report Covering 
Period from September 15 through October 15, 1944, 
T. H. Wheeler and Benjamin Fogler, Arthur D. Little, 
Inc., Oct. 23, 1944. Div. 11-102.213-M4 




BIBLIOGRAPHY 


411 


152. Development of Jest Unit for Production of Oxygen 

by it Regenerative Chemical, Progress Report Covering 
Period from October 15 through November 15, 1944, 
T. H. Wheeler and Benjamin Fogler, Arthur D. Little, 
Inc. Div. 11-102.213-M4 

153. Development of J'est Unit for Production of Oxygen 

by a Regenerative Chemical. Progress Report Covering 
Period from November 15 through December 15, 1944, 
T. H. Wheeler and Benjamin Fogler, Arthur D. Little, 
Inc. Div. 11-102.213-M4 

154. Development of Test Unit for Production of Oxygen 

by a Regenerative Chemical, Progress Report Covering 
Period from December 15, 1944 through January 15, 
1945, T. H. Wheeler and Benjamin Fogler, Arthur D. 
Little, Inc. Div. 11-102.213-M4 

155. Development of J'est Unit for Production of Oxygen 

by a Regenerative Chemical, Progress Report Covering 
Period from January 15 through February 15, 1945, 
T. H. Wheeler and Benjamin Fogler, Arthur D. Little, 
Inc. Div. 11-102.213-M4 

156. Development of J'est Unit for Production of Oxygen 
by a Regenerative Chemical, Progress Report Covering 
period from February 15 through March 15, 1945, T. H. 
Wheeler and Benjamin Fogler, Arthur D. Little, Inc. 

Div. 11-102.213-M4 

157. Experimental Finned-l ube Unit, Informal Monthly 

Progress Report for January 1942, E. R. Gilliland, 
R. D. McCrosky, and W. E. Catterall, MIT, January 

1942. Div. 11-102.213-MI 

158. Investigation of Oxygen Supply, R. D. McCrosky and 

W. E. Catterall. MIT, February 1942. 

Div. 11-102.21-MI 

159. Investigation of Oxygen Supply, Monthly Report for 

February 1942, R. D. McCrosky, W. E. Catterall, and 
others, MIT. Div. 11-102.21-M2 

160. Investigation of Oxygen Supply, Monthly Report for 

March 1942, R. D. McCrosky, W. E. Catterall, and 
others, MIT. Div. 11-102.21-M2 

161. Investigation of Oxygen Supply, Monthly Report for 

April 1942, R. D. McCrosky, W. E. Catterall, and 
others, MIT. Div. 11-102.21-M2 

162. Investigation of Oxygen Supply, Monthly Report for 

May 1942, R. D. McCrosky, W. E. Catterall, and 
others, MIT. Div. 11-102.21-M2 

163. Investigation of Oxygen Supply, Monthly Report for 

June 1942, R. D. McCrosky, W. E. Catterall, and others, 
MIT. Div. 11-102.21-M2 

164. Investigation of Oxygen Supply, Monthly Report for 

June to July 1942, R. D. McCrosky, W. E. Catterall, 
and others, MIT. Div. 11-102.21-M2 

165. Investigation of Oxygen Supply, Monthly Report for 

July to August 1942, R. D. McCrosky, W. E. Catterall, 
and others, MIT. Div. 11-102.21-M2 

166. Investigation of Oxygen Supply, Monthly Report for 

September 1942, R. D. McCrosky, W. E. Catterall, and 
others, MIT. Div. 11-102.21-M2 

167. Investigation of Oxygen Supply, Monthly Report for 


October 1942, R. D. McCrosky, W. E. Catterall, and 
others, MIT. Div. 11-102.21-M2 

168. Investigation of Oxygen Supply, Monthly Report for 

November 1942, R. D. McCrosky, W. E. Catterall, and 
others, MIT. Div. 11-102.21-M2 

169. Monthly Report for December 1942, R. D. McCrosky, 
W. E. Catterall, and others, MIT. Div. 11-102.21-M2 

170. Monthly Report for January 1943, R. D. McCrosky, 
W. E. Catterall, and others, MIT. Div. 11-102.21-M2 

171. Monthly Report for February 1943, R. D. McCrosky, 
W. E. Catterall, and others, MIT. Div. 11-102.21-M2 

172. Letter to E. P. Stevenson, Subject: Standard Appara¬ 
tus to Be Used in the Evaluation of the Absorption 
Properties of the Various Compounds Considered in the 
Oxygen Program, W. E. Catterall, Feb. 3, 1943. 

173. Biological Effects of Carbon Monoxide, W. E. Catterall, 

MIT, Feb. 18, 1943. Div. 11-106.2-MI 

174. Letter to Earl P. Stevenson, Subject: Design of Air¬ 

craft Unit, W. E. Catterall and J. C. Harper, MIT, 
Feb. 18, 1943. Div. 11-102-M5 

175. Monthly Report for March 15, 1943, R. D. McCrosky, 

W. E. Catterall, and others, MIT. Div. 11-102.21-M2 

176. Adaptability of Mixed-Base Chelate Compounds to 
Adiabatic Operation, Charles R. Hetherington and 
W. E. Catterall, MIT, Mar. 29, 1943. 

Div. 11-102.211-M19 

177. Further Studies on the Deterioration of Ethorninc and 

Salcomine, W. E. Catterall and A. M. Smith, MIT, 
Apr. 2, 1943. Div. 11-102.211-M20 

178. Monthly Report for March 15 to April 15, 1943, R. D. 
McCrosky, W. E. Catterall, and others, MIT. 

Div. 11-102.21-M2 

179. Regenerative Chemical Field Medical Unit, W. E. Cat¬ 
terall and Charles R. Hetherington, MIT, May 6, 1943. 

Div. 11-102.21-M5 

180. Monthly Report for April 15 to May 15, 1943, R. D. 
McCrosky, W. E. Catterall, and others, MIT. 

Div. 11-102.21-M2 

181. Monthly Report for May 15 to June 15, 1943, R. D. 
McCrosky, W. E. Catterall, and others, MIT. 

Div. 11-102.21-M2 

182. Salcomine: Monthly Report Covering Period June 15 to 
July 15,1943, Robert L. von Berg, MIT. 

Div. 11-102.212-M12 

183. Characteristics of the Oxygen Absorbents Ethorninc' 
and Fluorine, Report to June 30, 1945, Robert L. von 
Berg, OSRD 5407, MIT, July 31, 1945. 

Div. 11-102.211-M43 

184. The Preparation of o-Ethavan, Monthly Report Cover¬ 
ing Period February 10 to April 15, 1943, O. J. Wein- 
kauff, Monsanto Chemical Company. 

Div. 11-102.211-M16 

185. The Preparation of o-Ethavan, Monthly Report Cover¬ 
ing Period of April 16 to May 15, 1943, O. J. Wein- 
kauff, Monsanto Chemical Company. 

Div. 11-102.211-M16 

186. Progress of the Research on Salcomine and Related 
Compounds, Report for September 1942, Karl A. Holst, 






412 


BIBLIOGRAPHY 


Rum ford Chemical Works, Oct. 15, 1942. 

Div. 11-102.212-M9 

187. Progress of the Research on Salcomine anil Related 
Compounds, Monthly Report for October 1942, Karl A. 
Holst, Rumford Chemical Works, Nov. 12, 1942. 

Div. 11-102.211-M10 

188. Progress of the Research on Salcomine and Related 
Compounds, Monthly Report for January 1943, Karl A. 
Holst, Rumford Chemical Works, Feb. 11, 1943. 

Div. 11-102.211-M13 

189. Progress of the Research on Salcomine and Related 
Compounds, Monthly Report for February 1943, Karl 
A. Holst, Rumford Chemical Works, Mar. 12, 1943. 

Div. 11-102.211-M13 

190. Progress of the Research on Salcomine and Related 
Compounds, Monthly Report, Karl A. Holst, Rumford 
Chemical Works, Apr. 21. 1943. Div. 11-102.211-M13 

191. Progress of the Research on Salcomine and Related 
Compounds, Monthly Report for May 1943, Karl A. 
Holst, Rumford Chemical Works, May 21, 1943. 

192. Monthly Report Covering Period from May 15 to 
June 15,1943, Karl A. Holst, Rumford Chemical Works, 
June 21, 1943. 

193. The Development of a Method for Preparing Large 
Quantities of Fluornine, Informal Report Covering 
Period from February 1 to March 24, 1944, Karl A. 
Holst, Rumford Chemical Works. 

Div. 11-102.211-M36 

194. Production of Salcomine and Related Compounds, Karl 
A. Holst, OSRD 6052, Rumford Chemical Works, 
Sept. 4, 1945. 

195. Production of Oxygen by the Use of a Regenerative 

Chemical, Wendell M. Latimer, OSRD 126, University 
of California, Aug. 25, 1941. Div. 11-102.211-M3 

196. An Improved Method for the Manufacture of Active 
Colbalt Salicylaldchydccthylencdiaminc, Melvin Calvin, 
OSRD 403, University of California, Dec. 29, 1941. 

197. Manufacture of Oxygen by Use of Regenerative Chem¬ 

icals, Melvin Calvin, OSRD 403, University of Cali¬ 
fornia, Dec. 29, 1941. Div. 11-102.211-M5 

198. Informal Monthly Report in form of Letter to E. P. 
Stevenson from Melvin Calvin, University of California, 
Feb. 14, 1942. 

199. Report on Chelate Oxygen Compounds, Melvin Calvin, 
University of California, December 1942. 

200. Chelate Compounds for Oxygen Production, Summary 
Covering Period from February 1 to March 1, 1943, 
Melvin Calvin, University of California, March 1943. 

Div. 11-102.211-M17 

201. Monthly Report, April 1 to May 1, 1943, Melvin Calvin, 
University of California. 

202. Summary Report, June 1 to June 30, 1943, Melvin 
Calvin, University of California. 

203. Report for July, 1943, Melvin Calvin, University of 
California. 

204. The Laboratory Preparation of 3-FluorosalicylaIdchyde 
zvith Suggestions for Pilot Plant Production, L. Fergu¬ 


son, R. Holmes, and others, University of California, 
Oct. 15, 1943. Div. 11-102.211-M30 

205. The Manufacture of 50 Lbs. of 3-F-Salicylaldchyde, 
Melvin Calvin, University of California, Dec. 9, 1943. 

Div. 11-102.211-M31 

206. The Forms and Methods of Preparation of Cobalt bis- 

(3-FluorosaIicylaldchydc) Ethylcncdiiminc, R. H. Bailes 
and Melvin Calvin, University of California, Feb. 1, 
1944. Div. 11-102.211-M31 

207. A Report Covering the Preparation of 75 Lbs. of 3- 

Fluoro-Salicylaldchydc and 20 Lbs. of the Active Cobalt 
Chelate, Melvin Calvin, et ah, University of California, 
Apr. 10, 1944. Div. 11-102.211-M37 

208. Oxygen Carrying Chelate Compounds, Progress Report 
Covering Period from June 1 to August 31, 1944, Melvin 
Calvin', University of California. Div. 11-102.211-M39 

209. Chelate Compounds, Monthly Report, T. A. Geissman, 
William G. Young, and others, University of California 
at Los Angeles, Mar. 15, 1942. Div. 11-102.211-M7 

210. Chelate Compounds, Monthly Report for March 15 to 
April 15, 1942, T. A. Geissman, William G. Young, and 
others, University of California at Los Angeles. 

Div. 11-102.211-M8 

211. Chelate Compounds, Monthly Report for April 15 to 
May 14, 1942, T. A. Geissman, William G. Young, and 
others, University of California at Los Angeles. 

Div. 11-102.211-M8 

212. Chelate Compounds, Monthly Report for May 15 to June 
15, 1942, T. A. Geissman, William G. Young, and others, 
University of California at Los Angeles. 

Div. 11-102.211-M8 

213. Chelate Compounds, Monthly Report for June 15 to July 
15,1942, T. A. Geissman, William G. Young, and others, 
University of California at Los Angeles. 

Div. 11-102.211-M8 

214. Chelate Compounds, Monthly Report for July 15 to Aug¬ 
ust 15, 1942, T. A. Geissman, William G. Young, and 
others, University of California at Los Angeles. 

Div. 11-102.211-M8 

215. Chelate Compounds, Monthly Report for August 15 to 
.September 15, 1942, T. A. Geissman, William G. Young, 
and others, University of California at Los Angeles. 

Div. 11-102.211-M8 

216. Chelate Compounds, Monthly Report for September 15 
to October 15, 1942, T. A. Geissman, William G. Young, 
and others, University of California at Los Angeles. 

Div. 11-102.211-M8 

217. Chelate Compounds, Monthly Report for October 15 to 
November 15, 1942, T. A. Geissman, William G. Young, 
and others, University of California at Los Angeles. 

Div. 11-102.211-M8 

218. Chelate Compounds, Monthly Report for November 15 

to December 15, 1942, T. A. Geissman, William G. 
Young, and others, University of California at Los 
Angeles. Div. 11-102.211-MS 

219. Chelate Compounds, Monthly Report for December 15 
1942 to January 1, 1943, T. A. Geissman, William G. 





BIBLIOGRAPHY 


413 


Young, and others, University of California at Los 
Angeles. Div. 11-102.211-M8 

220. Chelate Compounds, Monthly Report for January 1 to 
February 1,1943, T. A. Geissman and William G. Young 
and others, University of California at Los Angeles. 

Div. 11-102.211-M8 

221. Chelate Compounds, Monthly Report for February 1 to 
March 1, 1943 , T. A. Geissman, William G. Young 
and others, University of California at Los Angeles. 

Div. 11-102.211-M8 

222. Chelate Compounds, Monthly Report for March 1 to 
April 1, 1943, T. A. Geissman, William G. Young and 
others, University of California at Los Angeles. 

Div. 11-102.211-M8 

223. Chelate Compounds, Monthly Report for April 1 to May 
1, 1943, T. A. Geissman, William G. Young and others, 
University of California at Los Angeles. 

Div. 11-102.211-M8 

224. Chelate Compounds, Report for the Month of May, 1943, 
University of California at Los Angeles. 

Div. 11-102.211-M22 

225. Chelate Compounds, Monthly Report for May 1 to June 
1, 1943, T. A. Geissman, William G. Young and others, 
University of California at Los Angeles. 

Div. 11-102.211-M8 

226. Chelate Compounds, Monthly Report for June 1 to July 
1, 1943, T. A. Geissman, William G. Young, and others, 
University of California at Los Angeles. 

Div. 11-102.211-M8 

227. Studies on the Deterioration of Ethomine^ Report Cov¬ 

ering Period from June 1 to September 1, 1943, John D. 
Roberts and R. O. Clinton, University of California 
at Los Angeles. Div. 11-102.211-M26 

228. Studies on the Deterioration of Salcomine, Report Cov¬ 

ering Period August 1 to October 1, 1943, John D. 
Roberts and R. O. Clinton, University of California at 
Los Angeles, October 1943. Div. 11-102.212-M14 

Chapter 12 

1. Peroxide Oxygen Generator, Final Report to October 1, 

1943, Walter M. Buehl and John E. Seubert, OSRD 1948, 
E. I. du Pont de Nemours and Company Inc., Oct. 25, 
1943. Div. 11-102.221-M2 

2. Generation of Oxygen from Alkali Peroxides, S. S. 
Prentiss, OSRD 1722, Aug. 24, 1943. 

Div. 11-102.221-MI 

3. Non-Rcgcncrative Chemical Methods of Producing Oxy¬ 
gen, S. S. Prentiss, Oct. 6, 1942. Div. 11-102.22-MI 

4. Survey of Oxygen Rebreathers, Letter of Transmittal and 
Report, Don M. Yost, Aug. 25, 1942. Div. 11-102.222-MI 

5. “Breathing Apparatus for Self-Rescue from Regions of 
Non-Inhalable Gas,” M. Bamberger and F. Bock, Zeits- 
chrift fur angewandte Chemie, 17, (1904), p. 1426. 

6. A Pump-Type Nitrogen Eliminator for the Navy High 
Altitude Rebreather, Don M. Yost, Don S. Martin, and 
J. E. Seegmiller, Apr. 13, 1943. 

7. 14th Progress Report on Chemical Oxygen Systems, R. 
R. Miller, et al., Naval Research Laboratory, 1943. 


8. Test of NRL Chemical Oxygen Unit for Navy Re¬ 
breather, W. Bowen, National Institute of Health, 1944. 

9. A Simplified Rebreather, S. Goldschmidt, A. Chambers, 
and G. Millikan, Report to U. S. Navy, Bureau of Aero¬ 
nautics, Sept. 26, 1944. 

10. A System for Using KOX As a Light, Compact Source 
of Oxygen for Bailing Out, W. J. Bowen, National Insti¬ 
tute of Health, TED No. 2512, July 1944. 

11. The C-K Oxygen Unit, A Chemical Demand System, 
G. A. Millikan, S. Goldschmidt, A. Chambers, and V. 
Gegallais, Johnson Foundation and Laboratory of Physi¬ 
ology, University of Pennsylvania, CAM No. 443, June 
1945. 

12. Report on the Performance of the MSA Navy Type 
Oxygen Rebrcathing Apparatus for Aircraft Use, A. H. 
Chambers and S. Goldschmidt, CAM No. 350, Sept. 10, 
1944. 

13. Report on Comparison of GOX and KOX Chemicals, J. 
N. Stannard, National Institute of Health, May 8, 1943. 

14. Effect of Center Screen Separator on Performance of 
KOX Canisters, G. E. Reynolds, W. E. Pricer, J. N. 
Stannard, National Institute of Health, Report E-36-N- 
BuAero, Nov. 11, 1943. 

15. The Nitrogen Meter, J. C. Lilly and T. F. Anderson, 
CAM Report No. 299, Johnson Foundation, University of 
Pennsylvania, Feb. 28, 1944. 

16. C. E. Berthollet, Mem. Acad. Fran., (1785). 

17. Treatise on Inorganic Chemistry, J. W. Mellor, Vol. II. 

18. J. Scobai, a. f. Phy. Chem. 44, (1903), p. 319. 

19. E. Blau and R. Weingand, a.f.Elcktroch, 27 (1921), p. 1. 

20. Fry and Otto, J.Amer.Chcm.Soc. 45 (1923), p.l 138. 

21. Patents: I. G. Farbenind, A. G. Ger. 566, 780, Feb. 20, 
1932; I. G. Farbenind, A. G. Ger. 568, 124, Mar. 13, 1933; 
Kate Wurster, Ger. 579, 424, June 26, 1933; Marcel 
Manon, Fr. 758, 827, Jan. 24, 1934; I. G. Farbenind, 
A. G. Ger. 807, 355, Jan. 11, 1937; I. G. Farbenind, 
A. G. Ger. 636, 639, Oct. 12, 1936. 

22. A. Hloch, Z. Angew, 43 (1930), p. 732, also Chem. Zeit. 
57 (1933), p. 533. 

23. Intelligence Report to NRL from Naval Attache in 
London, Serial 2409, Aug. 26, 1942. 

24. Report 22, Munitional Supply Laboratories, Maribyrnon, 
Melbourne, Australia. 

25. Wright Field Eng. Report No. 49-660-45H, Dec. 20, 1943. 

26. Technical Air Intelligence Report No. 40 OP-NAV- 
16VT240, John R. Pappenheimer, May 1945. 

27. Report on British Oxygen Candles, OSRD 1327, A. D. 
Little Company, Mar. 10, 1943. 

28. NRL Report to Director, D. S. Burgess, C-JC10, June 7, 
1943. 

29. Conference, NRL, NDRC, Oldbury Chemical Company, 
MSA Company, Dec. 17, 1943. 

30. NRL Report to Chief, BuAero, Ens. W. H. Schechter, 
C-JC10-1, May 11, 1945. 

31. Goodwin and Kalmus, Phys. Rev. 28 (1909), p. 10. 

32. “Mercury Poisoning,” A. M. Fraser, K. I. Melville, and 



414 


BIBLIOGRAPHY 


R. L. Stehle, /. Ind. Hyg. 16 (1934), p. 77. 

33. The Layering Economiser, John R. Pappenheimer and 
John C. Lilly, CAM Report No. 359, August 1944. 

34. Handbook of Respiratory Data in Aviation, Nat. Res. 
Council, CAM 1944. 

35. Measurement of Inspiratory and Expiratory Air Veloci¬ 
ties at Altitude, John R. Pappenheimer and John C. Lilly, 
Report 208, University of Pennsylvania, Nov. 30, 1943. 

Div. 11-104.2-M2 

36. Development of Oxygen Candle Apparatus for Use in 

Aircraft, John R. Pappenheimer and others, University of 
Pennsylvania, U.S. Naval Research Laboratory, and 
other institutions. Div. 11-102.223-M2 

SUPPLEMENTARY 

1. Nitrogen Elimination in the Navy High Altitude Re¬ 
breather, Don M. Yost, Northwestern University, Nov. 

15, 1943. Div. 11-102.222-M3 

2. Nitrogen Elimination in the High Altitude Rebreather, 
Don M. Yost, Don S. Martin, and others, Nov. 15, 1942. 

Div. 11-102.222-M2 

3. Oxygen Producing KOX Chemical—Specifications for 
and Availability, from Director, NRL, to Chief, BuAero, 
Aug. 17, 1943. 

4. A Study of the Oxides of Potassium and Sodium, C. A. 
Kraus and E. F. Whyte, July 6, 1926. 

5. Use of Alkali Oxides in Canisters for Submarine Air 
Purification, from Director, NRL, to Chief BuShips, 
June 26, 1943. 

6. Improved Production of Sodium, A. G. Arend, Jan. 1, 
1943. 

7. Report on Manganese Absorbents in the Production of 
Oxygen from Air. 

Chapter 13 

1. Letter to Earl P. Stevenson, Subject: Low Pressure 

Oxygen Vaporizer, W. F. Giaque, University of Cali¬ 
fornia, Sept. 25, 1943. Div. 11-103.5-M4 

2. Liquid Oxygen Trailer Unit Design, Construction and 
Operation, Report to July 25, 1944, W. F. Giauque, 
OSRD 4141, University of California, Sept. 19, 1944. 

Div. 11-103.1-M7 

3. Final Report, John D. Akerman and J. Piccard. 

4. Liquid Oxygen Converter, W. W. Hay, Ohio Chemical 
and Manufacturing Co., Sept. 28, 1945. 

Div. 11-103.5-M12 

5. Problem Related to the Use of Liquid Oxygen and to 

Design and Operating Characteristics of Liquid Oxygen 
Converters, Meeting at University of Pennsylvania, July 
13, 1944. Div. 11-103.5-M13 

6. Liquid Oxygen Converter (Akerman), Test of TED- 
2547 (3rd), from Director of NRL to Chief of BuAero, 
Feb. 15, 1944. 

7. Report on Akerman Liquid Oxygen Converter Submitted 
by BuAero, Navy Dept. Washington D.C. on February 

16, 1943 (1st), L. J. Briggs, NBS, May 19, 1943. 


8. Liquid Oxygen, Dept, of Scientific Research and Experi¬ 
ment, Admiralty (File B-4444), March 1944. 

9. Liquid Oxygen Converter (Akerman), Test of TED- 
2547, from Director of NRL to Chief of BuAero, Apr. 25, 
1944. 

10. Oxygen Converters—Test of Dr. J. A. Mathis and Mr. R. 
Milan’s Apparatus, from Director of NRL to Chief of 
BuAero, Feb. 26, 1943. 

11. Tests of Akerman Oxygen Vaporizer Under Simulated 

Flight Conditions, S. S. Prentiss and John R. Pappen¬ 
heimer, May 4, 1944. Div. 11-103.5-M6 

12. Two Linde Liquid Oxygen Evaporators Submitted by the 

BuAero, Navy Dept., Washington D.C. on April 7, 1943, 
Lyman J. Briggs, National Bureau of Standards, May 
18, 1943. Div. 11-103.5-M2 

13. Design and Test of Hand-Operated Liquid Oxygen Pump 

for Charging High Pressure Cylinders, T. L. Wheeler 
and Allen Latham Jr., Arthur D. Little Inc., Sept. 2, 
1943. Div. 11-103.2-MI 

14. Problems Related to the Use of Liquid Oxygen and to 

Design, and Operating Characteristics of Liquid Oxygen 
Converters, S. S. Prentiss, University of Pennsylvania, 
July 1944. Div. 11-103.5-M7 

15. AMAE/DDQ, Subcommittee on Oxygen Equipment, H. 
Grayson Smith and J. C. Findlay, University of Toronto. 

16. Oxygen Converter, Revised Akerman Apparatus Devel¬ 
oped for NDRC, R. K. West, BuAero, Oct. 26, 1943. 

Div. 11-103.5-M5 

17. “The Use-of Liquid Oxygen for High Altitude Flying,” 

John D. Akerman, Reprinted from the Journal of Aero¬ 
nautical Science, 8, No. 9, July 1941, University of Minne¬ 
sota, July 1941. Div. 11-103.5-MI 

18. Performance Characteristics of Portable Liquid Oxygen 
Converters, V. J. Wulff, U. S. Army Air Forces, Air 
Technical Service Command, Mar. 15, 1945. 

Div. 11-103.5-M8 

19. Design Requirements and Test Results on Aircraft Type 
Liquid Oxygen Converters, V. J. Wulff, U.S. Army Air 
Forces, Air Technical Service Command, Mar. 25, 1945. 

Div. 11-103.5-M9 

20. NDRC-NBS-Ohio Chemical Conference on Liquid Oxy¬ 

gen Converters, W. A. Wildhack, National Bureau of 
Standards, Apr. 9, 1945. Div. 11-103.5-M10 

21. Trip Report—Transportation of Liquid Oxygen, From 
Lt. J. P. Layton to BuAero and BuS, Aug. 17, 1943. 

22. Patents: U.S. 2260357 Jenner, U.S. 1747366 Heylandt, 
Re 18476 Heylandt, Re 1773140 Heylandt, Re 18646 Hey¬ 
landt, Re 1786159 Heylandt, Re 18774 Heylandt, Re 
1812954 Heylandt, Fr. 708002 (1931) L’Oxhydrique In¬ 
ternationale. 

23. Evaluation of Oxygen Sources—Memo for Director of 
NRL, W. H. Sanders, July 14, 1943. 

24. Oxygen Converter—Test of the Akerman Apparatus 
(1st), Director, NRL, Feb. 8, 1943. 

25. Oxygen Converter—Test of Revised Akerman Appar¬ 
atus (2nd), Director of NRL to Chief of BuAero, Aug. 
4, 1943. 







BIBLIOGRAPHY 


415 


26. Technical Data Pertaining to Air: Its Liquification and 
Distillation, Walter E. Lobo, OSRD 5206, Oct. 6, 1944. 
(See Appendix in this volume.) 

Chapter 14 

1. Improvements in Instrument for Measuring the Partial 

Pressure of Oxygen, Linus Pauling, Reuben E. Wood, 
and J. H. Sturdivant, OSRD 779, Report No. 314 to 
July 10, 1942, California Institute of Technology, Aug. 
8, 1942. Div. 11-106.3-M2 

2. A Survey of the Pauling Oxygen Meter Project, Reuben 

E. Wood, California Institute of Technology, Sept. 14, 
1943. Div. 11-106.3-M5 

3. Performance of Model P Pauling Oxygen Meter in a 

Flying Airplane, Reuben E. Wood, California Institute of 
Technology, Sept. 1, 1943. Div. 11-106.3-M6 

4. The Pauling Oxygen Meter, Report to June 30, 1944, 
Reuben E. Wood and David P. Shoemaker, OSRD 4361, 
California Institute of Technology, Nov. 20, 1944. 

Div. 11-106.3-M8 

5. Pauling Oxygen Meter, California Institute of Tech¬ 
nology, Feb. 22, 1944. Div. 11-106.3-M7 

6. Oxygen Meters, Progress Reports covering period from 
March, 1942 to June 15, 1944, Linus Pauling, OEMsr- 
326, OEMsr-584, and NDCrc-200, California Institute of 
Technology, for the following dates: Jan. 14, 1942; 
Mar. 13, 1942; Apr. 15, 1942; May 12, 1942; June 13, 
1942; July 10, 1942; Aug. 11, 1942; Sept. 15, 1942; Oct. 
12, 1942; Nov. 11, 1942; Dec. 14, 1942; Feb. 15, 1943; 
May 15, 1943; June 22, 1943; July 19, 1943; Sept. 15, 
1943; Oct. 15, 1943; Nov. 15, 1943; Dec. 15, 1943; Feb. 15, 
1944; Mar. 15, 1944; Apr. 15, 1944; June 15, 1944. 

7. Final Report, Arnold O. Beckman. 

8. Oxygen Meter, Monthly Reports 1 and 2 Covering 

Period from November 15 to December 15, 1942, OEMsr- 
624, Arnold O. Beckman, California Institute of Tech¬ 
nology. Div. 11-106.3-M3 

9. Oxygen Meter, Monthly Reports 1 and 2, Covering Per¬ 

iod from November 15,1942 to December 15, 1942, Arnold 
O. Beckman, OEMsr-625, California Institute of Tech¬ 
nology. Div. 11-106.3-M4 

10. Methods of Production and Calibration of Combination 

Vapor Pressure and Gas Dial Thermometers, Paul Erb- 
guth and J. G. Aston, OSRD 4780, University of Penn¬ 
sylvania, Jan. 26, 1945. Div. 11-104.2-M5 

11. Combined Oxygen Vapor Pressure and Gas Thermome¬ 
ters for Use in Temperature Range — 320°F to 100°F, 
Donald S. Parker and Malcolm L. Sagenkahn, Pennsyl¬ 
vania State College, Sept. 24, 1943. Div. 11-104.2-MI 

12. Combined Oxygen Vapor Pressure and Gas Thermome¬ 
ter, Final Report to January 6, 1944, J. G. Aston, OSRD 
3483, Pennsylvania State College, Apr. 14, 1944. 

Div. 11-104.2-M3 

13. Instrument for Testing Water-Vapor Content and Carbon 
Monoxide Content in Aviator’s Oxygen, T. L. Wheeler 
and Gilbert W. King, Arthur D. Little, Inc., Jan. 5, 1944. 

Div. 11-106.21-M7 


14. Development of Instrument for Measuring Water-Vapor 

Content in Aviator’s Oxygen, Progress Reports covering 
period from February 1944 to February 1945, T. L. 
Wheeler, Gilbert W. King, and Allen Latham, Jr., Ar¬ 
thur D. Little, Inc. Div. 11-106.21-M8 

15. Instrument for Measuring Water-Vapor Content in Avi¬ 

ator's Oxygen, Report to April 11, 1945, T. L. Wheeler 
and Howard O. McMahon, OSRD 5151, Arthur D. Little, 
Inc., May 31, 1945. Div. 11-106.21-M9 

16. Differential Gauge Responsive to Varying Liquid Levels 
Under Pressure, Frederick G. Keyes, March 1, 1943. 

17. “Determination of Oxygen Concentration by Physical 
Means,” H. Rein, Abstracts from the Scientific and Tech¬ 
nical Press, No. 106. 

18. Test of A. D. Little Company’s Wafer Vapor Indicator, 
National Bureau of Standards to S. S. Prentiss, July 8, 
1944. 

19. Test of Oxygen Water-Vapor Indicator, TED No. NBS- 
2599, Director of NBS to Chief of BuAero., Jan. 20, 1944. 

20. Operation of the Electrical Water-Vapor Detector, Na¬ 
tional Bureau of Standards, May 1, 1943. 

Div. 11-106.21-M5 

21. Accuracy of the Electrical Method for Determining 

Water in Compressed Gases, National Bureau of Stand¬ 
ards, June 14, 1943. Div. 11-106.21-M6 

22. A Method for Measuring Water Vapor in Compressed 
Gases, National Bureau of Standards, Mar. 20, 1943. 

Div. 11-106.21-M4 

23. Letter to S. S. Prentiss. Subject: Determining Moisture 

in Oxygen, E. R. Weaver, National Bureau of Standards, 
Mar. 2, 1943. Div. 11-106.21-M3 

24. A Method for Measuring Water Vapor in Compressed 
Gases, National Bureau of Standards, Oct. 9, 1942. 

Div. 11-106.21-M2 

25. A Method for Measuring Water Vapor in Compressed 
Gases, National Bureau of Standards, July 10, 1942. 

Div. 11-106.21-MI 

26. Performance Tests of Pauling Oxygen Meter, Submar¬ 
ine Model, Director of NRL to Chief BuS., Mar. 17, 1944. 

27. Bell Laboratories Record, 17, No. 2. 

28. Naval Research Laboratory Report No. P 1986, Jan. 15, 
1943. 

29. Preliminary Instruction Sheet for the Operation of MSA 
Water-Vapor Indicator. 

30. Instruction for Operation of the Moisture Indicator, 
Arthur D. Little, Inc., July 11, 1945. Div. 11-106.21-M10 

Chapter 15 

1. Dispersion of Exhaust Gases in Sea Water, W. H. 
McAdams, OSRD 1238, MIT, Mar. 4, 1943. 

Div. 11-106.11-M4 

2. Operation of Diesel Engines on Oxygen, N. H. Rickies 

and H. L. Thwaites, OSRD 1425, Standard Oil Develop¬ 
ment Co., May 17, 1943. Div. 11-106.12-M5 

3. Processes for the Removal of Carbon Dioxide from the 
Atmosphere of a Submarine, Allan P. Colburn and Bar- 



416 


BIBLIOGRAPHY 


nett F. Dodge, University of Pennsylvania, Feb. 20, 
1944. Div. 11-105.22-M3 

4. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen [Report] to December 31, 1944, J. H. Rushton, 
W. L. McCabe, and Barnett F. Dodge, OSRD 4623. 

Div. 11-101-M7 

5. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen [Report] to November 30, 1944, J. H. Rushton, 
W. L. McCabe, and Barnett F. Dodge, OSRD 4516. 

Div. 11-101-M7 

6. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen [Report] to October 31, 1944, J. H. Rushton, 
W. L. McCabe, and Barnett F. Dodge, OSRD 4452. 

Div. 11-101-M7 

7. Operating Instructions for MIT Model S-Unit for Pro¬ 

ducing Liquefied Oxygen for Respiratory Use on Sub¬ 
marines and Other Purposes, Dudley A. Williams, MIT, 
Mar. 24, 1944. Div. 11-103.3-M5 

8. DuPont Modification of Tessie-duMotay Oxygen Proc¬ 
ess, Memo to Walter E. Lobo from J. F. Skelly, W. M. 
Kellogg Co., Dec. 16, 1942. 

Additional Reports of the University of Pennsylvania 
(OEMsr-934) 

(See also the Monthly Progress Reports.) 

1. Monthly Progress Report, March 15, 1943 to January 31, 
1944, J. H. Rushton. 

2. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for February 1944, 
J. H. Rushton, Barnett F. Dodge, and others, OSRD 
3523, University of Pennsylvania. Div. 11-101-M7 

3. Process for the Removal of Carbon Dioxide from the 
Atmosphere of a Submarine, A. P. Colburn and Bar¬ 
nett F. Dodge, Feb. 20, 1944. 

4. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report, J. H. Rushton, Bar¬ 
nett F. Dodge, and others, OSRD 3652, University of 
Pennsylvania. Div. 11-101-M7 

5. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for April 1944, J. H. 
Rushton, Barnett F. Dodge, and others, OSRD 3760, 
University of Pennsylvania. Div. 11-101-M7 

6. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for May 1944, J. H. 
Rushton, Barnett F. Dodge, and others, OSRD 3861, 
University of Pennsylvania. Div. 11-101-M7 

7. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for June 1944, J. H. 
Rushton, Barnett F. Dodge, and others, OSRD 972, Uni¬ 
versity of Pennsylvania. Div. 11-101-Kf7 

10. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for July 1944, J. H. 
Rushton, Barnett F. Dodge, and others, OSRD 4142, 
University of Pennsylvania. Div. 11-101-M7 

11. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for August 1944, J. H. 
Rushton, Barnett F. Dodge, and others, University of 
Pennsylvania. Div. 11-101-M7 


12. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for October 1944, 
J. H. Rushton, Barnett F. Dodge, and others, OSRD 
4201, University of Pennsylvania. Div. 11-101-M7 

13. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for November 6, 1944, 
J. H. Rushton, Barnett F. Dodge, and others, OSRD 
4302, University of Pennsylvania. Div. 11-101-M7 

14. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for December 30, 1944, 
J. H. Rushton, Barnett F. Dodge, and others, OSRD 
4516, University of Pennsylvania. Div. 11-101-M7 

15. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for January 24, 1945, 
J. H. Rushton, Barnett F. Dodge, and others, OSRD 
4623, University of Pennsylvania. Div. 11-101-M7 

16. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for January 31, 1945, 
J. H. Rushton, Barnett F. Dodge, and others, OSRD 
4732, University of Pennsylvania. Div. 11-101-M7 

19. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for May 30, 1945, 
J. H. Rushton, Barnett F. Dodge, and others, OSRD 
4879, University of Pennsylvania. Div. 11-101-M7 

20. Central Engineering Laboratory, NDRC, Section 11.1, 

Oxygen Monthly Progress Report for April 30, 1945, 
J. H. Rushton, Barnett F. Dodge, and others, OSRD 
5040, University of Pennsylvania. Div. 11-101-M7 

21. Central Engineering Laboratory, NDRC, Section 11.1, 
Oxygen Monthly Progress Report for May 31, 1945, 
W. L. McCabe, OSRD 5153, University of Pennsylvania. 

Additional Reports of the Massachusetts Institute of 
Technology (OEMsr-122 and NDCrc-82) 

1. Experimental Study of Disposal of Exhaust Gases from 

Internal Combustion Engines on Naval Vessels, Report 
to May 1, 1941, James B. Conant, W. H. McAdams, 
MIT, June 6, 1941. Div. 11-106.11-MI 

2. Monthly Progress Report, W. H. McAdams, Dec. 20, 

1941. 

3. Monthly Progress Report, W. H. McAdams, Jan. 15, 

1942. 

4. Disposal of Engine Exhaust Gases, Quarterly Report 
Nov. 1, 1941 to Feb. 1, 1942, W. H. McAdams. 

5. Monthly Progress Report for Work Ending February 
15, 1942, W. H. McAdams. 

6. Monthly Progress Report for February 15 to March 15, 
1942, W. H. McAdams, Mar. 14, 1942. 

7. Monthly Progress Report Covering Period March 15 to 
April 15, 1942, W. H. McAdams, Apr. 14, 1942. 

8. Disposal of Engine Exhaust Gases, Quarterly Report for 

the Period February 1, 1942, to May 1, 1942, W. H. 
McAdams, MIT, May 1942. Div. 11-106.11-M2 

10. Monthly Progress Report, May 15 to June 15, 1942, 
W. H. McAdams. 

11. Monthly Progress Report Covering Period June 15 ta 
July 15, 1942, W. H. McAdams, July 15, 1942. 




BIBLIOGRAPHY 


417 


12. Quarterly Report, W. H. McAdams, July 29, 1942. 

13. Monthly Progress Report Covering Period July 15 to 
August 15, 1942, W. H. McAdams, Aug. 12, 1942. 

14. Monthly Progress Report, Disposal of Exhaust Gases, 
W. H. McAdams, Sept. 15, 1942. 

15. Disposal of Exhaust Gases, Memo to E. P. Stevenson 
from W. H. McAdams, Oct. 27, 1942. 

16. Disposal of Exhaust Gases, Memo to E. P. Stevenson 
from W. H. McAdams, Nov. 2, 1942. 

Additional Reports of the Standard Oil Development 
Company (NDCrc-90) 

1. Letter to Dr. T. K. Sherwood, Subject. Special Engine 

Problem, W. J. Sweeney, Standard Oil Development 
Company, Nov. 27, 1940. Div. 11-106.12-MI 

2. Report on Engine Tests with Chemical Source of Oxy¬ 
gen, Serial No. 60, W. J. Sweeney, July 21, 1941. 

3. 5th Progress Report, Special Engine Project No. 41, 
H. L. Leland, W. W. Manville, G. H. Cloud, Standard 
Oil Development Company, Oct. 27, 1941. 

Div. 11-106.12-M2 

4. 6th Progress Report for Period October 15 to Decem¬ 
ber 2, 1941. 

5. Special Engine Project No. 41 for Period December 1940 
to December 1941, Formal Report, W. J. Sweeney, Dec. 
23, 1941. 

6. Special Engine Project No. 41, Informal Progress Re¬ 
port, G. H. Cloud, N. H. Rickies, and H. L. Thwaites, 
Jan. 20, 1942. 

7. Appendix to Report of Oxygen Conference, Tuesday, 
January 27, 1942, MIT, Feb. 9, 1942. Div. 11-106.12-M4 

8. 7tlx Progress Report-, G. H. Cloud, N. H. Rickies, and 
H. L. Thwaites, Feb. 16, 1942. 


9. 8th Progress Report, N. H. Rickies and H. L. Thwaites, 
Mar. 18, 1942. 

10. Special Engine Project No. 41—Von Scggern Engine, 

G. H. Cloud, Mar. 19, 1942. 

11. Report on Operation of Diesel Engines on Oxygen, 
OSRD 614, December 2, 1941 to April 16, 1942, G. H. 
Cloud, N. H. Rickies, and H. L. Thwaites. 

12. 8th Progress Report, G. H. Cloud, N. H. Rickies, and 

H. L. Thwaites, Apr. 18, 1942. 

13. Informal Progress Report, G. H. Cloud, N. H. Rickies, 
and H. L. Thwaites, Apr. 18, 1942. 

14. 10th Progress Report, June 15, 1942. 

15. 11th Progress Report, G. H. Cloud, N. H. Rickies, and 
H. L. Thwaites, July 15, 1942. 

16. 12th Progress Report, Aug. 27, 1942. 

17. Special Engine Project #41, 13th Progress Report, 
W. J. Sweeney, Sept. 18, 1942. 

SUPPLEMENTARY 

1. Maintaining a Normal Breathing Atmosphere in a Sub¬ 
marine, Research Memorandum 2-44 from Navy Bureau 
of Ships, Mar. 21, 1944. 

2. Air Purification in Submarines: (1) Minutes of meeting 
held August 12, 1943, and (2) paper dated October 12, 
1943, Northways, London. 

3. Submarine Propulsion Committee, Minutes of First Meet¬ 

ing Held at Admiralty, Dec. 1, 1936. 

4. Closed Cycle Operating Characteristics of a Diesel En¬ 
gine, Navy Dept. Report, Naval Research Laboratory 
Report 0-2205, L. F. Campbell, W. E. Whybrew, and 
W. H. Sanders, December 1943. 



418 


BIBLIOGRAPHY 


MICROFILMED BUT NOT IN BIBLIOGRAPHY 


[Trailer Unit for Producing Oxygen] Contract NDCrc-206 
with Air Reduction Company, Progress Report for August 
1942, Wolcott Dennis, Air Reduction Company, Inc., August 

1942. Div. 11-102-M2 

Oxygen Project, Frederick G. Keyes, NDCrc-182, Special 
Report 4, MIT, Apr. 15, 1942. Div. 11-102.1-M3 

Skid Mounted Oxygen Plant Designed and Built by the 
Research Laboratory of the Air Reduction Company, Inc., 
Stamford, Connecticut, Wolcott Dennis, Air Reduction Com¬ 
pany, Inc., June 15, 1943. Div. 11-102.12-M3 

The Design and Building of Tzvo Sizes of Turbo Expanders, 
OSRD 6670, The Sharpies Corporation, May 24, 1946. 

Div. 11-102.13-M4 

Salcomine, Brief Summaries of Investigations Covering Pe¬ 
riod from June 1942 to March 12, 1943, E. P. Bartlett, A. G. 
Weber, and others, E. I. du Pont de Nemours and Com¬ 
pany, Inc. Div. 11-102.212-M2 

Investigation of Oxygen Supply, Monthly Reports Covering 
Period from July 1942 to August 31, 1942, W. E. Catterall, 
A. M. Smith, and others, Massachusetts Institute of Tech¬ 
nology. Div. 11-102.212-M4 

A Re-Evaluation of the Toxicity of Salcomine, Excerpt from 
NDRC Informal Monthly Progress Report, No. 9-4-1-21, 
Oct. 10, 1944. Div. 11-102.212-M18 

The Lobo Unit, Reports for the months of August, October, 
and November 1942, F. H. Wells and W. S. Gleeson, Amer¬ 
ican Machine Defense Corporation. Div. 11-102.213-M2 

Oxygen Equipment [Development under] Contract No. 
OEMsr-499, Monthly Report for December 1942, F. H. 
Wells, American Machine Defense Corporation, Jan. 5, 

1943. Div. 11-102.213-M3 

Stability and Concentration of Hydrogen Peroxide, Fred¬ 
erick G. Keyes, W. C. Schumb, and D. B. Broughton, OSRD 
5385, OEMsr-1453, MIT, Aug. 1, 1945 Div. 11-102.221-M3 
Hydrogen Peroxide, H. S. Gardner and T. K. Sherwood, 
OSRD 5448, OEMsr-1453, MIT, Aug. 17, 1945. 

Div. 11-102.221-M4 

Laboratory Study of the Possibilities of. Commercial Syn¬ 
thesis of Hydrogen Peroxide by Electrical and Photo¬ 
chemical Methods, W. H. Rodebush, C. R. Keizer, and oth¬ 
ers, OSRD 6644, OEMsr-1452, University of Illinois, Mar. 
25, 1946. Div. 11-102.221-M5 

Chlorate Oxygen Candles, S. S. Prentiss, Oldbury Chemical 
Company, Dec. 17, 1943. Div. 11-102.223-MI 

The Liquid Oxygen Problem, Report Coz'cring Period from 
May 1 to June 30, 1941, by W. F. Giauque, June 1941. 

Div. 11-103.1-MI 

Shipboard Oxygen Liquid Unit, Wolcott Dennis and W. G. 
Fogg, Report 1826, NDCrc-206, Air Reduction Company Inc., 
June 1,1942. Div. 11-103.3-MI 

Liquid Oxygen Pump, J. P. Layton, BuAero Project 97/43, 
U.S. Naval Engineering Experiment Station, Annapolis, 
Maryland, Aug. 17, 1943. Div. 11-103.5-M3 

Akerman-Piccard Liquid Oxygen Converter, John D. Aker- 
man and Jean F. Piccard, OEMsr-364, University of Min¬ 
nesota, June 12, 1945. Div. 11-103.5-M11 

Letter to Walter E. Lobo, Subject: Rectification Problems, 
J. G. Aston, Pennsylvania State College, Jan. 4, 1942. 

Div. 11-104.11-MI 


Full Scale Studies of the Efficiency of Packed Columns in 
Air Rectification (Love Pressure System) in Collaboration 
with the M. IV. Kellogg Company, Monthly Report for the 
Period Ending June 30, 1942, J. G. Aston, Pennsylvania 

State College, July 15, 1942. Div. 11-104.12-M2 

Tests of Performance of an 8-Inch Portable Unit Column 

for Air Rectification, Progress Reports for Period July and 
August 1942, J. G. Aston and others, Pennsylvania State 
College. Div. 11-104.12-MI 

Tests of Performance of Portable Unit Columns for Ain 
Rcctificatiqn, Progress Reports for Period from August 1942 
to September 1943, J. G. Aston, Charles Brouse, and others, 
Pennsylvania State College. Div. 11-104.12-M3 

Analysis of the Ammonium Hydroxide-Ammonium Chlo¬ 
ride-Copper Method for High Oxygen Content Gases Con¬ 
taminated with Argon or Nitrogen, D. C. Reams, Jr., Central 
Engineering Laboratory, June 1, 1944. Div. 11-104.2-M4 
Dispersers, Monthly Progress Report for Period from No¬ 
vember 15 to December 15, 1941, W. H. McAdams, MIT, 
Dec. 20, 1941. Div. 11-106.111-MI 

Water Injection Disperser, Monthly Progress Report Cover¬ 
ing Period from January 15 to February 15, 1942, W. H. 
Adams, NDCrc-82, MIT, February 1942. Div. 11-106.111-M2 
Carbon Dioxide Gas, Monthly Progress Report Covering 
Period from February 15 to March 15, 1942, W. H. Mc¬ 
Adams, OEMsr-122, MIT, Mar. 14, 1942. 

Div. 11-106.111-M3 

Carbon Dioxide Gas, Monthly Progress Report Covering 
Period from March 15 to April 15, 1942, W. H. McAdams, 
OEMsr-122, MIT, Apr. 14, 1942. Div. 11-106.111-M4 

Tivo-Stage Water Injection Type.Gas Disperser, Monthly 
Progress Report covering Period from May 15 to June 15, 
1942, W. H. McAdams, OEMsr-122, MIT, June 15, 1942. 

Div. 11-106.111-M5 

Dispersion-Absorption Runs, Monthly Progress Report Cov¬ 
ering Period from June 15 to July 15, 1942, W. H. McAdams, 
OEMsr-122, MIT, July 15, 1942. Div. 11-106.111-M6 

Tzvo-Stagc Water Injection Dispersers, Quarterly Report 
for Period Ending July 31, 1942, W. H. McAdams, OEMsr- 
122, MIT, July 29, 1942. Div. 11-106.111-M7 

Two-Stage Dispersers, Monthly Progress Report Covering 
Period from July 15 to August 15, 1942, W. H. McAdams, 
OEMsr-122, MIT, Aug. 12, 1942. Div. 11-106.111-M8 

Letter to T. K. Sherwood, Subject: Special Submarine En¬ 
gine Problem, W. J. Sweeney, Standard Oil Development 
Company, Nov. 27, 1940. Div. 11-106.12-MI 

Special Engine Project 41, Fifth Progress Report, G. H. 
Cloud, H. L. Leland, and W. W. Manville, NDCrc-90, 
Standard Oil Development Company, Oct. 27, 1941. 

Div. 11-106.12-M2 

Special Engine Project 41, Monthly Reports Covering Per¬ 
iod from December 2, 1941 to September 15, 1942, G. H. 
Cloud, N. H. Rickies, and H. L. Thwaites, NDCrc-90, Stand¬ 
ard Oil Development Company. Div. 11-106.12-M3 

Appendix to Report of Oxygen Conference, Tuesday, Janu¬ 
ary 27, 1942, W. J. Sweeney, MIT, Feb. 9, 1942. 

Div. 11-106.12-M4 



OSRD APPOINTEES 


DIVISION 11 


Division 11 was organized on December 9, 1942, when 
former Division B of the NDRC was broken up into four 
new Divisions—8, 9, 10, and 11—known as the Chemical Divi¬ 
sions. Former Division B was under the chairmanship of 
Roger Adams and had ten sections, each of which had one 
or more subsections. Division 11 was made up of Sections 
B-7, B-8, part of B-9, and B-10 (together with subsections 
B-7-b, B-7-d, B-7-e, B-8-a, B-8-b, B-8-c, B-8-d, B-8-e, B-8-f, 
B-9-a, and B-9-d) of former Division B. Subsections B-9-b 
and B-9-c of Section B-9 later became Division 19. 

The list which appears below therefore shows essentially 


the organization since December 9, 1942. Although many 
changes were made during the years 1943-1945, the names of 
all appointees who held appointments to Division 11 at any 
time during this period have been included. In addition the 
names of men who held appointments in the sections and 
subsections of former Division B but who did not have ap¬ 
pointments to Division 11 following the reorganization have 
been included so as to give a complete picture of the organiza¬ 
tion since the beginning of the work under NDRC. 

Section 11.1 comprises Subsection B-7-b of former Divi¬ 
sion B. 


Division Chiefs 

R. P. Russell E. P. Stevenson 

H. M. Chadwell 


Division Technical Aide 

D. Churchill, Jr. 


Division Members 


D. Churchill, Jr. 

E. R. Gilliland 
H. C. Hottel 
H. F. Johnstone 


W. K. Lewis 
J. H. Rushton 
R. P. Russell 
T. K. Sherwood 


E. P. Stevenson 


section i 

Section Chiefs 

E. P. Stevenson J. H. Rushton 


Section Technical Aides 


D. Babcock 
W. W. Beck 
S. C. Collins 
D. R. Dewey 


C. C. Furnas 
IT. B. Goff 
S. S. Prentiss 
J. H. Rushton 


Section Members 


T. H. Chilton 

B. F. Dodge 

C. C. Furnas 

E. R. Gilliland 


W. R. H AINSWORTH 

F. G. Keyes 
W. H. McAdams 
F. J. Metzger 

W. J. Sweeney 


419 


CONTRACT NUMBERS, CONTRACTORS, AND SUBJECT OF CONTRACTS 


Contract No. 

NDCrc-82 

NDCrc-90 

NDCrc-38 

NDCrc-129 

NDCrc-182 

NDCrc-198 

NDCrc-200 

NDCrc-206 

OEMsr-4 

OEMsr-122 

OEMsr-215 

OEMsr-232 

OEMsr-269 

OEMsr-279 

OEMsr-326 

OEMsr-355 

OEMsr-364 

OEMsr-365 

OEMsr-370 

OEMsr-395 

OEMsr-454 

OEMsr-499 

OEMsr-530 

OEMsr-584 

OEMsr-604 

OEMsr-605 


Name and Address of Contractor 


Subject 


Massachusetts Institute of Technology, 
Cambridge, Massachusetts 
Standard Oil Development Company, 

26 Broadway, New York, N.Y. 
California Institute of Technology, 
Pasadena, California 
University of California, 

Berkeley, California 
Massachusetts Institute of Technology, 
Cambridge, Massachusetts 
University of California, 

Berkeley, California 
California Institute of Technology, 
Pasadena, California 
Air Reduction Company, Inc., 

60 East 42nd Street, New York, N.Y. 
Massachusetts Institute of Technology, 
Cambridge, Massachusetts 
Massachusetts Institute of Technology, 
Cambridge, Massachusetts 
Iowa State College, 

Ames, Iowa 
Yale University, 

New Haven, Connecticut 
Arthur D. Little, Inc., 

30 Memorial Drive, Cambridge 42, Mass. 
University of California, 

Berkeley, California 
California Institute of Technology, 
Pasadena, California 
Yale University, 

New Haven, Connecticut 
University of Minnesota, 

Minneapolis, Minnesota 
The M. W. Kellogg Company, 

225 Broadway, New York, N.Y. 

Clark Brothers Company, Inc. 

Olean, New York 
University of California, 

Los Angeles, California 
The Linde Air Products Company 

5502-5524 Second Ave., Brooklyn, N.Y. 
American Machine and Foundry Company, 
30 East 42nd Street, New York, N.Y. 
Independent Engineering Company, 
O’Fallon, Illinois 

California Institute of Technology, 
Pasadena, California 

E. I. du Pont de Nemours and Company, 
Wilmington, Delaware 
Rumford Chemical Works, 

Rumford, Rhode Island 


Disposal of exhaust gas from submarines. 

Engine performance tests with special fuels. 

Oxygen analyzer. 

Regenerative oxygen-absorbing compounds (Salcomine). 

Design, construction, and testing of a pilot plant liquid- 
oxygen producer. 

Design, construction, and testing of a mobile liquid oxygen 
plant utilizing the cascade system. 

Oxygen analyzer. 

Rectifying column for use in oxygen-generating plants and 
design and construction of a mobile oxygen unit. 

Apparatus for generating oxygen with regenerative oxygen¬ 
absorbing compounds. 

Disposal of exhaust gas from submarines. 

Regenerative oxygen-absorbing compounds. 

Experimental study of devices for oxygen production. 

Construction and testing of miscellaneous types of apparatus 
for producing and handling oxygen. 

Regenerative oxygen-absorbing compounds. 

Improvements in Pauling meter. 

Testing of apparatus for oxygen production. 

Design and construction of liquid oxygen vaporizers. 

Design and engineering of oxygen-producing units. 

Construction of mobile oxygen units and apparatus therefor. 

Synthesis and study of regenerative oxygen-absorbing com¬ 
pounds. 

Study and analysis of oxygen cycles. 

Development and construction of apparatus for producing 
oxygen from Salcomine. 

Development and construction of mobile oxygen-producing 
units utilizing Salcomine. 

Development of oxygen partial-pressure indicators for use 
on submarine and aircraft. 

Investigation of methods of producing oxygen from Salco¬ 
mine suspended in liquid media. 

Manufacture of large batches of Salcomine. 


420 




CONTRACT NUMBERS, CONTRACTORS, AND SUBJECT OF CONTRACTS ( continued ) 


Contract No. 

Name and Address of Contractor 

Subject 

OEMsr-624 

A. 0. Beckman, 

South Pasadena, California 

Manufacture of Pauling meters on orders approved by 
OSRD. 

OEMsr-625 

A. O. Beckman, 

South Pasadena, California 

Development of Pauling meters for use on submarines. 

OEMsr-654 

J. F. Pritchard and Company, 

2200 Fidelity Bank Building, 

Kansas City, Missouri 

Construction of equipment for large liquid-oxygen pilot 
plants. 

OEMsr-666 

The Sharpies Corporation, 

23rd and Westmoreland Streets, 
Philadelphia, Pennsylvania 

Development and construction of turbo expanders. 

OEMsr-685 

Pennsylvania State College, 

State College, Pennsylvania 

Testing of oxygen-producing equipment. 

OEMsr-798 

Elliott Company, 

J eannette, Pennsylvania 

Design and development of turbo compressors and expanders. 

OEMsr-863 

E. I. du Pont de Nemours and Company, 
Wilmington, Delaware 

Design and construction of generators for producing oxygen 
from alkali peroxides. 

OEMsr-903 

Monsanto Chemical Company, 

St. Louis, Missouri 

Development of method for making ortho-ethavan. 

OEMsr-914 

Servel, Inc., 

51 East 42nd Street, New York, N.Y. 

Construction of small liquid-oxygen units. 

OEMsr-934 

University of Pennsylvania, 

Philadelphia, Pennsylvania 

Central laboratory for the oxygen program. 


421 







SERVICE PROJECTS 

The projects listed below were transmitted to the Executive Secre¬ 
tary, NDRC, from the War or Navy Department through either the 

War Department Liaison Officer for NDRC or the Office of Research 
and Inventions (formerly the Coordinator of Research and Develop¬ 
ment), Navy Department. 

Service 
Project No. 

Sub jcct 

AC-12 

AC-32 

CE-29 

Army Projects 

The Manufacture of Oxygen while in Flight for Use of the Combat Crew. 

Lubricants for Use with Oxygen at High Pressure. 

Field Generation of Oxygen. 

Navy Projects 

NA-106 

NA-111 

NA-138 

Development of Oxygen Breathing Equipment and Associated Apparatus. 

Portable Unit for Supplying Oxygen. 

Compact Apparatus for Determining Suitability of Oxygen for Use in Aircraft at High Altitude, Develop¬ 
ment of 

NL-Bl(f) 

NL-B6 

NL-B6(b) 

NL-B6(c) 

NL-B6(d) 

NL-B42 

NS-115 

NS-116 

NS-117 

NS-226 

Development of an Instrument for the Measurement of Oxygen Partial Pressures. 

Operation of Submarine Engines while Submerged. 

Engine Tests on Oxygen-Supplying Chemicals; Oxygm and Oxygen-Containing Fuels. 

Absorption of Exhaust Gases. 

Equipment for Manufacture of Liquid Oxygen. 

Development of Chemicals and Apparatus for Regenerative Production of Oxygen. 

Liquid Oxygen Plant. 

Portable Unit for Producing Oxygen for Welding and Cutting and Breathing Oxygen Aboard Aircraft. 
Oxygen-Producing Apparatus for Repair Ship Installation. 

Submarine Air Conditioning with Liquid Oxygen. 


422 





INDEX 


The subject indexes of all STR volumes are combined in a master index printed in a separate volume. 
For access to the index volume consult the Army or Navy Agency listed on the reverse of the half-title page. 


Acetylene determination, colorimetric 
method, 240 

Acetylene removal from air, 229 
Activated carbon, 39 
Adiabatic operation of salcomine cycle, 
258 

Aerofin tube cooler, 48, 50 
Air and air components, 343-392 
argon, 354-358 
carbon dioxide, 370-375 
composition, 144 
density of air, 387 

enthalpy entropy diagram of air, 380 
enthalpy of air, 376 
helium, 367-369 
nitrogen, 344-353 
oxygen, 359-366 

temperature entropy diagram of air, 
388,389 

thermal conductivity of air, 390 
viscosity of air, 391 
Air compressors, 59-74 
Bobtail compressor, 68-70 
centrifugal compressors, 60 
displacement blowers, 60 
Elliot-Lysholm rotary type, 65-68 
low-pressure and intermediate-pres¬ 
sure, 72 

low-pressure combined with engine 
drive, 68-70 

low-pressure dry air compressors, 62 
low-pressure oil lubricated, 60-61 
non-lubricated, 62, 65-68 
portable high-pressure compressors, 
70 

reciprocating air compressors, 60 
specifications, 60, 61, 63, 69, 71, 74 
turbo compressors, 60 
types, 59, 60 

Air conditioning in submarines, 335, 
338 

Air cooling 

see Heat exchangers 
Air drying 

by solid adsorbents, 192 
design factors, 194 
high-pressure air dryer, 193 
low-pressure air dryer, 193 
Air purification, 192-235 
acetylene removal, 229 
air drying, 192-194 
carbon dioxide removal, 194-198 
combustible contaminants removal, 
228-235 

Air Reduction Company 

gaseous oxygen production unit, 51- 
53 


medium-pressure oxygen unit (M-6), 
30 

mobile unit for liquid air fractiona¬ 
tion, 181 

test towers for liquid air fractiona¬ 
tion, 174 

Air-acetylene bombs, 233 
Air-activated liquid oxygen pump, 40 
Airco compartment trays, 173 
Aircraft oxygen units 
chlorate-primed KOX unit, 292 
C-K rebreather, 273-280 
Collins-McMahon unit, 182 
liquid oxygen vaporizers, 297 
oxygen meter, 317 
rebreather oxygen unit, 271-273 
sodium chlorate candle, 281-283 
wing units for oxygen production in 
flight, 259 

Air-transportable oxygen units 
airborne Collins unit, 68-70 
M-3 medium capacity unit, 25 
M-7AT unit, 24 

Akerman liquid oxygen vaporizer, 296, 
298 

Alkali chlorates for oxygen generation, 
268 

Alkali peroxides for oxygen generation, 
268-270 

Alkaline absorbents of carbon dioxide, 
204-206 

Alumina, 39, 48, 118 
American Instrument Company, 309 
Analytical equipment for oxygen 
plants, 239 

Argon in air, 354-358 
Arnold O. Beckman Co., 316, 318-320 
Aro Equipment Corp., 307-308 
Arthur D. Little, Inc., 296, 323 
Asbestos paper filters for liquid oxy¬ 
gen, 236 

Aviation rebreather, 273 

Axial turbine (expansion engine), 85 

Baralyme, 215 

Barium salts for carbon impregnation, 
107-109 

Bastian Blessing Company, 23 
Beattie-Bridgman equations, 220 
Beckman Laboratories, 312, 316, 318— 
320 

Bell Telephone Laboratories, 109, 314 
Benzophenone, 321 
Berl saddle packing, 154, 163 
Beryllium-copper alloy for oxygen 
pump cylinders, 115 
Bobtail compressor, 68-70 


Breathing bag for C-K rebreather unit, 
276-277 

“Briquette” (chlorate), 282 
British experiments with chlorate gen¬ 
erators, 273, 282 
Bureau of Mines, 231 
Butane as a refrigerant, 44 

C. B. Hunt & Son, 23 
California Institute of Technology, 
316-318 

Canister, gas mask, 274 
Carbon adsorbing traps 
graphitic, 102, 112 
impregnated, 109 
non-graphitic, 112 

Carbon dioxide determination, analyti¬ 
cal methods and equipment, 200, 
239 

Carbon dioxide in air, 370-375 
Carbon dioxide removal from air 
by active absorbents at low tempera¬ 
tures, 217 

by caustic solutions, 194-198 
by solid absorbents, 198-200, 204, 

215 

in submarines, 337-339 
“life” tests, 211 

solid carbon dioxide removal, 57, 219, 
221-222 

Carbon monoxide, catalytic oxidation, 
230 

Carbon rings for non-lubricated com¬ 
pressors, 99 
Carding teeth, 154 

Cascade refrigeration principle, 44, 45 
Catalyst Research Corporation, 276 
Catalytic oxidation of acetylene, 230- 
" 231 

Catalytic oxidation of carbon monox¬ 
ide, 230 

Caustic solution for removal of carbon 
dioxide from air, 39, 118, 194— 
198 

Centrifugal compressors, 60 
Centrifugal expander, 11 
Charcoal, Columbia 4ACW, 217 
Chelates, metal, 247 
Chemicals as a source of oxygen, 242- 
294 

“Chlorate-primed KOX” 
see C-K rebreather unit 
Chlorates as a source of oxygen 
see Sodium chlorate candles 
Chromium oxide for carbon dioxide re¬ 
moval from air, 218 


423 


424 


INDEX 


Circulating-solid system of salcomine 
oxygenation, 257 
C-K rebreather unit, 273-280 
components, 274-278 
efficiency, 291 
operation, 278 

physiological requirements, 280 
recommendations for further devel¬ 
opment, 279 
uses, 279 

Clark Company Bobtail compressor, 
68-70 

Clark dri-oxygen compressor, 93-112 
carbon rings, 101 
four-stage model, 96, 104 
improvements, 105 
ring wear tests, 107 
safety tests, 104 
specifications, 94, 97 
TFE piston rings, 102 
two-stage model, 93 
Clark 450-HP air compressor, 74 
Clark high-pressure portable air com¬ 
pressor, 70 

Clark-Collins expansion engines, 78-84 
Claude cycle for oxygen production, 

4-5 

Cobalt chelates for oxygen generation 
see Ethomine; Methomine; Salco¬ 
mine 

Cobalt complexes, 245-246, 248-251 
“Cold box only’’ oxygen unit, 25 
Collins airborne unit, 10-11 
Collins heat exchangers, 11, 119 
Collins small-sized reciprocating ex¬ 
pander, 74-78 
Collins tube, 119 

Collins-McMahon differential reboiler, 
187 

Collins-McMahon unit, 182 
Colorimetric determination of carbon 
dioxide, 201, 240 

Colorimetric method of acetylene deter¬ 
mination, 240 

Columbia 4ACW charcoal, 217 
Combustible contaminants, removed 
from air, 228-235 

Committee on Medical Research, 281— 
282 

Components of air 
see Air and air components 
Compressors 
see Air compressors 
Condenser-reboiler, 137 
Cooksville Company, 156 
Cooling atmospheric air to low tem¬ 
peratures 

see Heat exchangers 
“Co-ordinated reflux,” tray system, 169 
“Co-x- Sal-en,” 251 
“Critical bed length,” definition, 211 


Cycles for the mechanical separation of 
oxygen from air, 4-9 
Cylinder liners for oxygen compres¬ 
sors, 101 


Dalton’s law, 148, 220 
Dew point of C0 2 , 57 
Dial thermometer, pressure-actuated, 
239 

Diamagnetic gases, 310 
Diesel engine operation in submerged 
submarine, 330 

Differential distillation, McCabe-Thiele 
diagram, 187 

Differential reboiler, 182, 187 
Direct expansion refrigeration plant, 

39 

Displacement blowers, 60 
Distillation of oxygen from air 
see Liquid air fractionation 
Dittus-Boelter equation, 125, 127, 130 
Double-tower system for liquid air 
fractionation, 143 
Dry oxygen compressors, 93-112 
Dry Zero kapok insulation, 236 
Drying air by solid adsorbents, 192 
“Duplex” rectifier, Keyes, 142 
Du Pont Co., 271 


E. B. Badger unit, 51, 181-182 
Electrostatically balanced oxygen me¬ 
ters, 318-320 

Elliot-Lysholm rotary air compressor, 
60, 65-68 
Ethane, 44 
Ethomine, 243-267 

deterioration in cyclic operation, 265— 
267 

engineering evaluation, 256 
oxygenation cycle, 257-264 
oxygenation—deoxygenation reac¬ 
tion, 249-256 
preparation, 243-249 
thermal properties, 256 
Ethyl magnesium bromide, 321 
Ewell packing, 155 

Exhaust gas disposal from submarines, 
332-333 

Expansion engines for oxygen liquefac¬ 
tion, 74-92 
axial turbine, 85 
Clark-Collins 2-cylinder, 78 
Clark-Collins 2-cylinder high-pres¬ 
sure, 83 

Clark-Collins 2-cylinder walking 
beam type, 81 

Collins small reciprocator, 74-78 
turbo-expanders, 85, 89 
Explosions in oxygen plants, causes, 
228-235 


Ferric oxide for carbon dioxide re¬ 
moval from air, 218 
Fiberglas tower packing, 155, 236-239 
Filters for oxygen plants, 236-239 
Fisher pellet KOH, 215 
Fisher pellet NaOH, 215 
Fluidized system of salcomine oxygena¬ 
tion, 257 

Fluomine, 243-267 

deterioration in cyclic operation, 265- 
267 

engineering evaluation, 256 
oxygenation cycle, 257-264 
oxygenation—deoxygenation reac¬ 
tion, 249-256 
preparation, 243-249 
thermal properties, 256 
Fort Belvoir fractionation unit, 179-181 
Foxboro frost point instrument, 323, 
326 

Fractionating column for shipboard 
operation, 174-176 
Fractionation of air 

see Liquid air fractionation 
Frankl-type regenerators, 119, 133 
Freon refrigeration system, 46, 51, 181 
Frost-point instrument for determining 
moisture content of gases, 323- 
328 

Gas phase pressurized liquid oxygen 
vaporizer, 304 

Gas thermometer for low temperatures, 
328 

Gaseous oxygen production 
Air Reduction Co. unit, 51 
LeRouget plant M-31 ; 53 
M-l unit, 47 
M-2 unit, 11-14 
M-3 unit, 25 
M-7 unit, 14 
M-7 AT unit, 24 

Gases for catalytic oxidation of acety¬ 
lene, 231 

German chlorate oxygen supply unit, 
282 

Giauque equation, 126 
Giauque liquid air fractionation mobile 
unit, 181 

Giauque liquid oxygen mobile unit, 44 
Giauque liquid oxygen vaporizer, 297 
Giauque modification of the double 
tower, 143 

Giauque-Hampson exchanger, 119, 127, 
128, 130 

Glass raschig rings, 159 
Graphitic carbon, 102, 112 
Grignard reagents, 321 

Haldane apparatus, 200 
Hampson-type exchangers, 126 



INDEX 


425 


Hand operated liquid oxygen pump, 116 
Harrisburg bombs, 231-233 
Haydite tower packing, 156, 166 
Heat exchangers, 118-138 
Collins exchanger, 119-120 
Giauque exchanger, 126 
Giauque-Hampson exchanger, 119, 
127 

Hampson-type, 126 
high-pressure, 118-119, 125-131 
liquefier and subcooler, 124 
low-pressure, 118, 120 
recommendations, 130 
rectangular multipin, 122 
regenerator type, 118, 131-137 
reversing exchangers, 119 
RLHL type, 129 
switch exchangers, 119 
Heat transfer coefficients 
Dittus-Boelter equation, 125, 127, 

130 

for high-pressure air inside tubes, 

126 

for low-pressure air outside tubes, 
128-130 

for regenerators, 135-137 
Giauque equation, 126 
McAdams method of determining, 

125 

Heat transfer in coils, 127 
Heat transfer in high-pressure heat ex¬ 
changers, 130 

Heat transfer rates in Collins ex¬ 
changer packing, 120 
Heat transfer with salcomine beds, 256 
Helium in air, 367-369 
HETP (height of packing equivalent 
to a theoretical plate), 143 
Hoch, oxygen unit employing briquette, 
282 

Hopcalites, 230-231 

HTU (height of packing in a transfer 
unit), 143 

Hydrocarbons in air, 240 
“Hytrotarder,” 83 

Impregnated carbon, 109 
Independent Engineering Co. liquid 
feed double-tower system, 142 
Independent Engineering Company 
tray tower, 166 

Instruments for determining moisture 
content of gases, 320-323 
Instruments for testing oxygen, 309- 
329 

Insulating materials for liquid air frac¬ 
tionation plants, 236-241 
Japanese chemical oxygen generator 
for aircraft, 282 

Jet dispersion of submarine engine ex¬ 
haust while submerged, 332 


Jet-type scrubber, 196-198 

Johnson Foundation, 274, 281-282, 300 

Joule-Thomson cycle, 39, 42, 48 

Kapitza type centrifugal expander, 11 
Kellogg M-l gaseous oxygen unit, 47- 
51 

Kellogg M-2 gaseous oxygen unit, 11- 
14 

Kellogg M-5 regenerator plant, 26 
Kellogg M-7 gaseous oxygen plant, 14- 
24 

Kellogg tray tower, 166, 179 
Ketones, for detection of water vapor, 
320 

Keyes “duplex” rectifier, 142 
Keyes liquid oxygen production unit, 
39, 131, 217 

Kipp gas generator, 270 

Latham liquid oxygen unit, 42 
Lead iodide, 107-109 
Legallais valve, 278 
LeRouget plant M-31 ; 53 
Lessing rings, 159 

Lewis and Randal, fugacity rules, 220 
Lilly nitrogen meter, 280 
Linde Air Products vaporizer, 296 
Linde cycle for oxygen production, 4, 
48,51 

Linde-Frankl cycle for oxygen produc¬ 
tion, 10-11, 85 

Liquefied oxygen injector pump, 112 
Liquid air fractionation, 139-164 
air-water testing of trays, 183-187 
effect of tower alignment, 152 
effect of tower pressure, 151 
large column packing tests, 163-165 
liquid distribution, 161 
methods of tray calculations, 144-147 
rocking column tests, 171-174 
rotary rectifiers, 176-177 
shipboard operation, 174-176 
small column tests, 151, 176 
theoretical tray calculations, 188 
theory,143 

trays, 148-150, 173-174, 186, 189 
vapor-liquid equilibrium, 148 
Liquid air fractionation, tower packing 
materials, 154-162, 188-189 
Berl saddles, 154, 163 
carding teeth, wire and glass helices, 
154 

Ewell packing, 155 
Fiberglas, 155 
glass Raschig rings, 159 
Haydite, 156, 166 
Lessing rings, 159 
metal textile packing, 161 
regenerator packing, 159 
shoe eyelets, 161 


Stedman packing, 161, 162, 164 
Liquid air fractionation, tower systems, 
140-143 

double column, 142, 143, 166 
duplex rectifier, 142 
liquid-feed tower, 140 
vapor-feed tower, 141, 190 
Liquid air fractionation, tray towers, 
143, 166-171 

Independent Engineering Co. tower, 
166 

M. W. Kellogg tray tower, 166-168 
type C-2 tray, 168 
type D tray, 169 
West tray, 169 

Liquid air fractionation, units, 177— 

183 

Air Reduction Co. mobile unit, 181 
Collins-McMahon unit, 182 
E. B. Badger unit, 181-182 
Fort Belvoir unit, 179-181 
Giauque unit (M-4), 181 
list of units, 139 
M-5 low-pressure unit, 182 
M-6 medium-pressure unit, 182 
M-7 mobile low-presure unit, 178— 
179 

Liquid level gauge, dial-type, 328-329 
Liquid oxygen, properties, 295 
Liquid oxygen, uses, 295 
Liquid oxygen converters 
see Liquid oxygen vaporizers 
Liquid oxygen production 
see also Liquid air fractionation 
Giauque unit, 44 
Keyes unit, 39, 131, 217 
large capacity plants, 25 
Latham unit, 42 
LeRouget plant M-31 ; 53 
Little-Latham generator, 131 
M-5 unit, 26 
M-6 unit, 30 
Liquid oxygen pumps 
air-activated, 40 
design and operation, 112 
hand operated, 116 
use, 93 

Liquid oxygen vaporizers 
Akerman model, 298, 300 
gas phase pressurized model, 304 
Giauque model, 297 
portable vaporizer, 306 
recommendations, 308 
types, 296 
uses, 295, 297 

Liquifier and subcooler, 124 
Little-Latham liquid oxygen generator, 
42, 131 

LP plants, use of low-pressure dry air 
compressor, 62 

LP-1 oxygen production unit (M-7), 17 




426 


INDEX 


Lysholm type rotary compressor, 60, 
65-68, 89 

M-l gaseous oxygen unit, 47-51 
M-l liquid air fractionation system, 143 
M-l portable high-pressure air com¬ 
pressor, 70 

M-2 gaseous oxygen unit, 11-14 
M-2 regenerators, 119 
M-3 air-transportable oxygen unit, 25 
M-5 liquid oxygen unit 
air compressor, 72 
description, 26 

fractionation column, 176, 182 
heat exchanger, 27-30, 122, 131 
regenerator plant, 26 
specifications, 34 
turbine expansion engine, 85 
M-6 liquid oxygen unit 
air compressor, 72 
design and operation, 34 
expansion engine, 83 
fractionation tower, 182 
heat exchanger, 131 
M-7 gaseous oxygen unit 
acetylene analysis, 229 
description, 14 
dry air compressor, 62 
filters, 236-239 
heat exchanger, 122-123, 131 
Kellogg tray tower, 179 
performance tests, 16 
production model (LP-1), 17 
M-7AT gaseous oxygen unit 
air compressor, 62 
description, 24 
production model, 24 
M-31 portable oxygen production unit, 
53 

Magnetic oxygen meter, 239, 280, 309- 
310 

Magnetic susceptibility of oxygen, 310 
Mathis vaporizer, 296 
McAdams method of determining heat 
transfer coefficients, 125 
McCabe-Thiele diagram of differential 
distillation, 187 

Mechanical cycles for oxygen produc¬ 
tion, 4-9 

Medical therapy with chlorate oxygen, 
293 

Metal textile tower packing, 161 
Metal-oxide catalysts, 230 
Methomine, 243-267 
deterioration in cyclic operation, 
265-267 

engineering evaluation, 256 
oxygenation cycle, 257-264 
oxygenation—deoxygenation reac¬ 
tion, 249-256 
preparation, 243-249 


thermal properties, 256 
Methyl magnesium iodide, 321 
Micarta rings for oxygen compressors, 
99-101 

Michler’s ketone, 321 
Milan vaporizer, 296 
Mine Safety Appliances Company 
frost point instrument, 323, 326 
ignition system for sodium chlorate 
candles, 281-282, 286 
Mobile gaseous oxygen unit, 11-14 
Mobile liquid oxygen unit, 39, 93, 118- 
120 

Moisture content of gases, 323 
Moisture content of oxygen, 320-321 
Moisture content of soda lime, 216 
Molybdenum plating for cylinder 
liners, 109 
Morgan, 102 
Morganite, 102 

Multipin heat exchangers, 122 
Murphree efficiency, 148 
“Naszogen,” 282 

National Bureau of Standards, 304, 

309, 328 

National Institute of Health, 280 
Naval Research Laboratory, 273, 281, 
282 

Navy aviation rebreather, 273 
“Nitralloy” steel, 74-78 
Nitrogen as a refrigerant, 10, 44, 50 
Nitrogen in air, 344-353 
Nitrogen meter, 280 
Nitrogen-argon mixtures in air, 384 
Nitrogen-oxygen mixtures in air, 392 
Non-graphitic carbon, 112 
Non-regenerative chemicals for oxygen 
production, 268-294 

Oil removal from compressed air, 236 
Oil-lubricated air compressor, 60 
Oldbury Electro-Chemical Company, 
273, 281-283 

Oldbury oxygen candle apparatus, 282 
Organic chelate compounds, 2 
Or sat method of oxygen analysis, 231, 
239 

Oximeter, 280 

Oxygen, magnetic susceptibility, 310 
Oxygen administered for therapeutic 
purposes, 271 

Oxygen analysis equipment, 239 
Oxygen candle apparatus (OCA), 281— 
294 

apparatus, 288-292 
foreign experiments, 282 
Naval Research Laboratory experi¬ 
ments, 282 
Oldbury model, 282 
physiological tests, 292 
sodium chlorate generators, 283-288 


uses, 281, 292 

Oxygen compressors, 93-117 
see also Liquid oxygen production 
Clark dri-oxygen compressors, 105 
four-stage non-lubricated, 96 
liquid oxygen pump, 112-116 
portable compressors, 96-98 
two-stage non-lubricated, 93 
use, 93 

Oxygen distillation from air 
see Liquid air fractionation 
Oxygen for aviator breathing, 93 
Oxygen from non-regenerative chemi¬ 
cals, 268-294 

rebreather unit for aircraft use, 271— 
281 

sodium chlorate candle for aircraft 
use, 281-294 

Oxygen from regenerative chemicals 
see Ethomine; Fluomine; Metho¬ 
mine ; Salcomine 
Oxygen in air, 359-366 
Oxygen mask, Army and Navy A-14; 
274 

Oxygen meters 
airplane model, 317 
CIT models A, B, and C, 316-318 
electrostatically balanced, 318-319 
Model P Pauling, 316 
other models, 318 
Pauling, 310 

submarine model (Model D), 316 
Oxygen production 
air compressors, 59-74 
air drying, 192 
air purification, 192-235 
air-transportable units, 24, 25, 68-70 
analytical methods and equipment, 

239 

carbon dioxide removal from air, 194 
catalytic oxidation of acetylene, 
230-231 

chemical methods, 242-294 
combustible contaminants removed 
from air, 228 

criteria for plant design, 8-9 
cycles, 4-11, 39 
expansion engines, 74-92 
explosion in oxygen plants, 228 
for aircraft use, 271-273, 281-283, 295 
for engineering use, 295 
for medical use, 295 
from alkali peroxides, 268-270 
from chlorates, 281 
from cobalt chlorates, 242-267 
from non-regenerative chemicals, 
268-294 

from regenerative chemicals, 242-267 
gaseous oxygen plants, 10-25, 47-57 
heat exchangers, 118-131 
high-pressure cycles and units, 39-57 




INDEX 


427 


in aircraft, 259 
in Germany, 10-11 
in submarines, 330-342 
liquid air fractionation, 139-191 
liquid oxygen plants, 25-51, 53-57 
liquid oxygen pumps, 112 
liquid oxygen vaporizers, 295 
low-pressure cycles and units, 10-38 
mechanical separation from air, 8-57 
medium-pressure unit, 30 
methods, 4-9 

military requirements, 4-9 

miscellaneous equipment, 236 

oxygen compressors, 93 

oxygen testing instruments, 309-329 

portable unit, 53 

reboilers, 137-138 

regenerator, 131-137 

sodium chlorate candle apparatus, 

281 

Oxygen supply maintenance in subma¬ 
rines, 337 

Oxygen testing instruments 

chemical method for moisture deter¬ 
mination, 320 

combined vapor-pressure and gas 
thermometer, 328 
deflection-type meter, 316-318 
dial-type liquid level gauge, 328-329 
electrostatically balanced instru¬ 
ments, 318-319 

frost point instrument, 323-328 
instrument for determining a combi¬ 
nation of properties, 328 
Models A, B, and C meters devel¬ 
oped at CIT, 316 

Model D meter (submarine model), 
316 

Model K meters, 317 
Model L meter (airplane model), 317 
Model P Pauling oxygen meter, 316 
null-type meter, 318 
Pauling oxygen meter, 309-315 
Oxygen-argon mixtures in air, 385 
Oxygenation-deoxygenation reaction, 

249-256 

Oxygen-nitrogen mixtures in air, 377— 
383, 386 

Packed columns for carbon dioxide re¬ 
moval from air, 194 
Packings for liquid air fractionation 
towers 

see Liquid air fractionation, tower 
packing materials 
Paramagnetic gases, 310 
Parkersburg Rig and Reel Co., 83 
Pauling oxygen meter, 239, 280, 309- 
315 

Pennsylvania State College tower, 
packing tests, 159 


Peroxides for oxygen generation, 268- 
270 

Pettenkofer method of C0 2 analysis, 

200 

Pfund gas analyzer, 201, 240 
Phenyl magnesium iodide, 321 
Piccard vaporizer, 296 
Plates per transfer unit (PTU), 143 
Polymerized fluoro-carbon (TFE) for 
piston rings, 102 
Portable oxygen units 
air-transportable units, 24-25, 68-70 
Clark portable oxygen compressor, 
70, 96-97 

LeRouget Plant M-31 ; 53 
liquid oxygen vaporizer, 306 
mobile oxygen units, 11-14, 39, 93, 
118-120 

rebreather oxygen unit for aircraft 
use, 271-273 

sodium chlorate candle apparatus for 
aircraft use, 281 

trailer-mounted oxygen plants, 44, 
47, 51 

Potassium tetroxide for oxygen gener¬ 
ation, 2-3 

Pressure-actuated dial thermometers, 
239 

Productivity, definition, 259 
Progressive vaporizers, 187-188 
Purification of air, 192 

Radial turbine, 85 

Radiators for mobile oxygen units, 

131 

Raoult’s law, 148 
Raschig rings, 159 

Reactors for aircraft wing salcomine 
oxygenation units, 259 
Reboilers for oxygen plants, 137-138 
Rebreather oxygen unit for aircraft, 
271-273 

Reciprocating air compressors, 59 
Reciprocating expander, 74-78 
Recommendations for further research 
air conditioning submarines, 338 
chlorate oxygen uses in aircraft, 293- 
294 

C-K rebreather unit, 279-280 
combustible contaminants removed 
from air, 233-235 

diesel engine operation in submerged 
submarines, 331-332 
dry air compressor, 62-65 
engine exhaust disposal, submerged 
submarines, 335 
frost point instrument, 327-328 
Giauque-Hampson exchanger, 127 
high-pressure heat exchangers, 130 
liquid oxygen vaporizers, 308 


mobile oxygen plant of the future, 

57 

turbo-expander, large, 89 
water vapor detection with chemi¬ 
cals, 323 

Rectangular multipin heat exchanger, 

122 

Reflux ratio in liquid air fractionation, 
143 

Refrigeration plant, direct expansion, 

39 

Regenerative chemicals for oxygen 
production 

sec Ethomine; Fluomine; Metho- 
mine; Salcomine 
Regenerators, 10-11, 131-137, 159 
components, 133-134 
German, 10-11, 133 
heat transfer coefficients, 135 
packing, 159 
tests, 133 

Reversing heat exchangers, 119 
Ring tests for four-stage dri-oxygen 
compressor, 109 
RLHL heat exchangers, 129 
Rocking column tests for liquid air 
fractionation, 171 
Rotameter, 322 

Rotary compressors for use at liquid 
air temperature, 60, 65-68, 89 
Rotary rectifiers for liquid air fraction¬ 
ation, 176-177 

Rumford Chemical Works, 244 

Safety and fire hazard tests of oxygen 
compressor, 104 
Salcomine, 93-96, 242-267 
chemistry, 242 
crystal structure, 253, 254 
derivatives, 243, 251 
deterioration in cyclic operation, 
265-267 

dry oxygen compressor, 93-96 
engineering evaluation, 256 
industrial hazards, 267 
life tests, 259-261 
magnetic properties, 253 
oxygenation—deoxygenation cycle, 
249-264 

preparation, 243-249 
saturation, 259 
substitutes, 243 
thermal properties, 256 
toxicity of salcomine dusts, 267 
Santocel insulation, 152, 236 
Saturation, definition, 259 
Scrubbing towers, 133 
Sea water scrubbing for exhaust gases, 
submarines, 333 

Semi-adiabatic operation of salcomine 
cycle, 258 



428 


INDEX 


Shipboard oxygen units, 264, 266 
fractionation column, 171 
M-5 oxygen unit, 25 
Shoe eyelets tower packing, 161 
Short tray tower tests, 168 
Sight-Feed Generator Co., 271 
Single tower with vapor feed modifica¬ 
tions, 141 

Soda lime determination, field method, 
240-241 

Soda lime for carbon dioxide removal 
from air, 198-200, 202-217, 240- 
241 

Sodium chlorate candles, 281-294 
components, 288 
description, 283 
design factors, 288 
for C-K rebreather unit, 276 
foreign research 282 
ignition system, 286 
medical therapy, 293 
Oxygen Candle Apparatus (OCA), 
281 

physiological tests, 292 
purity of oxygen, 287 
recommendations, 293-294 
uses, 292, 293 

Sodi.im peroxide for oxygen genera¬ 
tion, 2 

Sodium salt of phenolphtalein, 201 
Solid absorbents for carbon dioxide re¬ 
moval from air, 198-200, 204, 
215-217 

Solid carbon dioxide removal from air 
streams, 221-222, 237-239 
Specifications 

Bobtail engine compressor unit, 69 
Clark 450-HP air compressor, 74 
Clark model HO-6-4 portable high- 
pressure compressor, 71 
Clark two cylinder vertical high- 
pressure expansion engine, 83 
Clark two-stage dri-oxygen compres¬ 
sor, 94 

Clark-Collins Model CCER-3 two- 
cylinder expansion engine, 80 
Clark-Collins walking beam two- 
cylinder expansion engine, 83 


four-stage dri-oxygen compressor, 97 
hand-operated liquid oxygen pump, 
116 

low-pressure dry air compressor, 63 
oil lubricator low-pressure air com¬ 
pressor, 61 

Stedman packing, 152, 161, 164 
Stedman tower, 42-44, 171 
Sturtevant blower, 48 
Submarines 

air conditioning, 335, 338 
carbon dioxide precipitation by re¬ 
frigeration, 219 

carbon dioxide removal from air, 339 
disposal of engine exhaust while sub¬ 
merged, 332-333 

operation of diesel engines while sub¬ 
merged, 330 
oxygen meter, 316 
oxygen production for, 330 
solid carbon dioxide removal, 221— 
222 

Switch exchangers, 119 


Tagliabue Mfg. Company, 328 
Taylor Instrument Company, 23 
Temperature measurement equipment, 
239 

TFE (Tetrafluroethane) piston rings, 

102 

Therapeutic administration of oxygen 
to patients, 271 

Thermal conductivity of salcomine, 256 
Thermocouples, copper-constantan, 239 
Thermometer, gas, 328 
Thermometer, pressure-actuated dial, 
239 

Titration method for carbon dioxide 
determination, 201, 239 
Towers for liquid air fractionation 
sec Liquid air fractionation, tower 
systems 

Towers for shipboard units and port¬ 
able plants, 174 

Toxicity of oxygen pumped with lead- 
carbon rings, 109, 112 


Toxicity of salcomine dusts, 267 
Trailer-mounted oxygen plants, 44, 47, 
51 

Trane Company, 124 
Transfer unit of a fractionation tower, 
143 

Tray towers for liquid air fractionation 
see Liquid air fractionation, tray 
towers 

Trays for fractionation towers, 186, 188 
Turbo compressors, 60 
Turbo-expander, 30-34, 85-89 

University of California, 126, 143, 296 
University of Minnesota, 298 
University of Pennsylvania Medical 
School, 273 

University of Pennsylvania Thermody¬ 
namics Research Laboratory, 92, 
124 

University of Toronto, 296-297 

Valves for liquid oxygen plants, 239 
van der Weals equation, limitations, 
220 

Vapor-feed air fractionation towers, 
147, 190 

Vapor-pressure and gas thermometer 
combined, 328 

Walk-around oxygen vaporizer, 306 
Water removal from pure oxygen, 192 
Water vapor detection by chemicals, 
320-323 

Water-lubricated oxygen compressor, 
96 

West trays for air fractionation towers, 
169 

Weston Electrical Instrument Com¬ 
pany, 23 

Wildhack vaporizer, 296 
Wire and glass helices, 154 
Wire gauze saddles, 182 
Wyandotte flake NaOH, 215 

Yale University, 151 

























































































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THE JOHNS HOP-KINS U.jJVERSITY 
Fi. L. J. Mci!Alfl 
WASHINGTON, 25, O.C. 








































































































































